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The Tumor Ablation Monthly Meeting occurs on the 3rd Tuesday of each month, 3-4pm, Abram's Conference Room. It is an open working meeting of the Tumor Ablation Program (TAP) intended to connect the TAP to the larger NCIGT community.

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August 15, 2008: 1. Cryotherapy at 3T; 2. RSNA


Present: SGSilverman, PRMorrison, Brendan Whalen, Kim Lawson, Noby Hata, Sota Oguro.

Cryotherapy at 3T

  • Bay 2 is due to come up on Sept 29
  • We reviewed Galil pdf regarding components for MRI install (junction boxes, gas lines etc)
  • Galil will be coming in to make measurements for gas lines etc
  • Initial ping being sent to Chistine Lorentz at Siemens who is in charge of iMRI
  • Discuss possible role for SLICER 3.2 in the environment
  • Related note made regarding Veran nav/tracking system demo for CT procedures
  • Noted that we do not have a monitor in Bay 2 to visualize images
  • Noted that image and heating tests of probes are still needed
  • Need meetings with technologists, nursing, anesthesia etc regarding pt care in 3T

RSNA 2008 - review of accepted ablation abstracts

  • Assessment of Percutaneous Liver Ablation with MRI: Value of Subtraction Images
  • Percutaneous Image-guided Cryoablation of Renal Tumors
  • Radiation Dose to Patients Undergoing CT-Guided Renal Cryoablation

April 18, 2008: Real-time Image Fusion for Biopsy & Ablation: Traxtal


Present: Paul Shea (VP Sales, Traxtal), Joe Dillon (Sales, Traxtal), SGSilverman, STatli, PRMorrison, DKacher, Rick Foley, BK Park, Karen Munkley.

Real-time Image Fusion for Biopsy & Ablation: Traxtal

  • Joe Dillon presented the technology to the group present.
  • This is the PercuNav system on the Traxtal platform. See Traxtal.com
  • Reviewed various elements of the device. Tool connection kit. US transducer tracker. Reference guide. Works with US only, or CT merged to US, or MRI merged to US.
  • System is electromagnetic. They make needles and devices with tracking elements in them.
  • Reviewed workflow with such a device. Operational issues.
  • They can connect with any US machine, though there is an alliance with Philips at present


  • SGS asks about specs for the room that will house the system to limit interference from CT or MRI or Computer Room nearby
  • Device is FDA approved
  • Some conversation about cost of system and implementation at US or CT on L1
  • Four other sites: NIH (B Wood). U Texas (C Dodd). MSK (S Solomon). MGH (P Mueller)
  • MGH site will actually come on line in early May.
  • Traxtal would like to re-visit BWH at that time (with CEO, Neil Glossup).

January 18, 2008: 1. CRYO@3T in 2008; 2. Probe Tests Needed; 3. Freezing at 3T


Present: SGSilverman, KTuncali, PRMorrison, Rick Foley

CRYO@3T in 2008

  • Reviewed current status of image guided ablation in general, and cryo-ablation in particular.
  • Reviewed 2006-2007 move into CT and acceleration of CT caseload after MRT went down.
  • Reviewed acceptability of CT, but motivation to return to MRI, and to add PET/CT.
  • Reviewed potential for 3T: 1. Returns MRI capability, 2.Wide bore, 3. Improved imaging over 0.5T or 1.5T, 4. Image within iceball for thermal mapping?
  • Projected to time when all image modalities available.

Probe Tests Needed

  • Experiments needed at 3T to test a) probe artifact and b) probe heating; in LMRC
  • We need to do some pre-clinical tests at 3T (focused worst-case scenarios).
  • Separately, we can also broaden variables to make this more of a publishable research project.
  • We want to confirm that probe artifact is not too bad, and that probes do not heat up significantly.
  • We look to collaborate with Imaging Core
  • We review documents:
  • doc: Galil’s imaging of probes at 3T in Oct 2004 and in June 2005 (imaging only; probes only; no ice)
  • doc: Presentation at the Nov Retreat by the NCIGT Imaging Core of prostate needles at 3T
  • doc: Simon DiMaio’s paper on artifact
  • doc: Sample professional testing of RFA electrode as mode for testing (imaging, attraction & heating)

Freezing at 3T

  • Consider cryo installation in LMRC to test a) device function in high field and b) image ice at 3T
  • Discuss motivation to test at 3T in LMRC.
  • Need better review of the imaging of probes.
  • Need to check on probe heating
  • Full install of cryo unit would let us look at operation of the device.
  • Further, if we install, we would be the first and only 3T cryo installation. This has not been done.
  • Thus, we could test for our satisfaction as we look toward 3T clinical use.
  • This could add to research and collaboration with physics group here.
  • It could be both an internal resource and a real NCIGT resource.


October 19, 2007: 1. Cryotherapy at 1.5T 2. Cryotherapy at 3T


1. Cryotherapy at 1.5T

2. Cryotherapy at 3T

September 21, 2007: 1. Respiratory Compensation for Intervention, 2. Mayo System, 3. BRREF Proposal


Present: PRMorrison, Paul Shyn, Nicu Archip, Steve Moore

Respiratory compensation for biopsy and ablation in PET/CT

  • Paul Shyn and Steve Moore converse a bit. PShyn describes the problem of needle-based interventions in organs that move with breathing that are performed when the patient is awake or sedated. One would like to comensate for the breathing such that the organs would be, in effect, motionless. This is important for planning and targeting lesions with needles and probes.
  • He noted that Varian has a laser-based device for respiratory compensation but it is expensive and perhaps a bit difficult for use in intervention as it is more a radiation therapy planning tool (used with pre-treatment PET and CT data). SM knows of the Varian system noting that it is nice in some ways with its passive tracking via the reflective markers which allow it to track motion (albeit in one direction only).

Mayo Interactive Breath-hold System

  • PShyn is interested in obtaining this Mayo device --- the "Mayo IBC" is a bellows-based device; the patient can use a visual aid to hold their breath at the same location for each scan.
  • One Question arises as to how long the leads are for the device, and whether they are suitable for PET/CT due to length of the bore.
  • SM notes that you can get "bins" of PET data. You could re-scan each 'snapshot' using scanner software and then, if needed, pull the images out for additional processing.
  • Note is made to compare this to an MSK publication. (Do we know what this is?)
  • Question arises regarding the scanner as to: If the breath is held, can you just press a button and acquire a scan? Any lag time?
  • Possible experiment: Measure registration of current method, i.e. free breathing PET/CT; then use this to measure any modifications to registration.
  • Note that the lesion as seen by PET is distorted; part of the plan would be to measure the distortion. * So, the free-breathing scans serve as a control (or current standard).
  • Next, do the scan with a breath-hold in a single bed position -- and hope to show better registration and less distortion.
  • Note that generally, hospitals do not do breath-hold PET scans.
  • Note that the scans are usually about 3 minutes per bed position, covering about 12-19 cm. This can be tweaked to accomodate intervention?
  • Note made that there is a '3D mode' in which the GE scanner can be run in (septa removed?). The Siemens scanners are all 3D mode (no septa?). Some mention of time-of-flight imaging.

Paul Shyn's BRREF Proposal

  • PaulS is submitting a BRREF grant to get money to buy the Mayo device.
  • We have some conversation about Methods for the grant and evaluation of the device's usefulness.
  • Can check validation of registration: Compare PET/CT free-breathing versus PET/CT with breath-hold over liver only.
  • Nicu proposes that the analysis could involve getting all the images into the same 'space' by non-rigid registration.
  • PShyn notes that part of method is to choose lesions that are seen on CT so that a measure of resistration can be made.
  • Perhaps could just measure the shift in the epicenter of the lesion?
  • Note: PET is distorted, CT is shifted.
  • The focus of the work is to see if the metabolic activity is where the anatomy is - what is the relation of the PET to the CT?
  • Thus: Can measure epicenter distance (#); Can measure edges and their shift (#); Can compute mutual information (#).
  • Note that a blurred distorted PET can lead to over-treating tissues. Could compare the lesion volume of the two PET scans (free breathing versus compensated).
  • So, Methods at this stage could use a paired t-test (since data compared is of the same pt) and look at shift and volumes.

August 17, 2007: 1. Closed Bore CRYO, 2. New Hata Collaboration Grant


Present: PRMorrison, STatli, NHata

Closed Bore CRYO – With MRT down and AMIGO implementation in process, cryotherapy has moved to CT-guidance only. There is a desire and clinical need to return MRI capability. The current plan is to install a cryo system in MRI Bay 1 and thus have closed bore MRI at 1.5T available until AMIGO is available and/or MRT resurrected.

  • Currently, the Galil cryotherapy system from MRT is being installed at Bay 1 by Dan Kacher. After this is completed, the plan is to have Galil representatives come and review/approve the installation for clinical use. This is due for Aug 23.
  • On 8/16, a dry run with the current installation was performed with physicians, nursing and technologists. 15 min freeze done; phantom; images to PACS.

New Hata Collaboration Grant – NCI awarded an RO1 on which Noby Hata is named as a collaborator. FAJ would like the work to have clinical traction with the ablation group.

  • NH reviewed that this is a system that is to be developed.
  • Grant is 1RO1CA124377 and should soon be on the wiki.
  • Specific Aims include semi-automatic segmentation (S.Haker of BWH is to do this)
  • BWH offers SLICER
  • GUMC offers IGSTK
  • The project involves EM tracking; BWH is to get a system
  • Noby possible to do a demo to Ablation team of Slicer 3 (new & coming), and to talk further about clinical application.

March 20, 2007: Non-Rigid Registration for Ablation


Present: SGS, PRM, ST, Nicu Archip

"Non-Rigid Registration for Ablation" - Current work in this regard center on the use of a non-rigid registration technique by which to A) register pre-procedural MRI to intra-procedural CT for tumor targeting and B) register pre-procedural MRI to post-procedural MRI to better assess tumor coverage.

  • Nicu provides a presentation on the progress on the work.
  • Hypotheses include improved targeting and quantification of outcomes.
  • To study improve targeting, image data from 13 RFA liver patients were analyzed. The new biomechanical method of registration was applied and compared against b-spline, demons and rigid techniques.
  • Validation methods included Normalized Mutual Information (NMI) and an edge distance based method.
  • Data shows good results for the new technique; good comparison against other techniques. Nearly double the accuracy of the best 'standard' techniques.
  • Next, Nicu showed results for registration of pre- to post-ablation MRI for assessment.
  • For this work: there is a poster that will be presented at the WCIO meeting in MAY, 2007. An R21 was recently submitted to the NIH; a MICCAI abstract was submitted; RSNA abstract likely to be submitted (two have been).
  • To implement the software for targeting clinically, we need to get a new computer to replace stolen one.


February 20, 2007: 1) Advanced CT Biopsy, 2) Image Subtraction


Present: SGS, PRM, ST, Marcelo Mamede, Eigil Samset, Arne Hans, George Oliviera

"Advanced CT Biopsy Project" - This is a CIMIT funded project for developing software for out-of-plane image guidance for needle/probe placement.

  • We reviewed the history of the grant; it is CIMIT funded work that had been awarded to Randy Ellis and with his departure, it went over to Eigil Samset.
  • The grant is for out-of-plane guidance for biopsy or radiofrequency ablation
  • The plan is to do a User Study in CT to see if the technology is worth pursuing.
  • Compare this to the work previously with Siemens on an augmented reality system: Das M, Sauer F, Schoepf UJ, Khamene A, Vogt SK, Schaller S, Kikinis R, vanSonnenberg E, Silverman SG. Augmented reality visualization for CT-guided interventions: system description, feasibility, and initial evaluation in an abdominal phantom. Radiology. 2006 Jul;240(1):230-5.
  • We review the software with a working demo brought by Eigil and Arne Hans.
  • The system has optical tracking on it now; note use of abdominal phantoms. This is the "dynamic reference system," it could use an EM tracking system. The software lets you pick image planes from a multi-slice acquisition. The planes are those that you monitor during the needle placement.
  • Colored crosshair icons in the image/FOV show RED, GREEN and BLUE for Needle, Tip and Virtual Extension , respectively.
  • Comment that a stiffer needle should be used for the tests. Start inferior and angle up. Recall this is for out-of-plane biopsy. Likely should include in-plane biopsy as part of testing as a sort of control.
  • Plan is to commence training of the physicians (SGS, KT, ST), and then do experiments on CT1.

"Image Subtraction for Ablation Assessment" review current "Methods"

  • Perhaps image follow-up should be at 3 months and not 24 hours due to acute inhomogeneous effects
  • Hypothesis includes that image subtraction will help assessment in the presence of short T1 effects in ablated areas
  • Call atention to the Bricault paper on assessment for liver RFA and PET. This reference may help in Methods. Note that it emphasizes the practical value of the approach: Bricault I, Kikinis R, Morrison PR, Vansonnenberg E, Tuncali K, Silverman SG. Liver metastases: 3D shape-based analysis of CT scans for detection of local recurrence after radiofrequency ablation. Radiology. 2006 Oct;241(1):243-50.
  • Does the subtraction help to detect residual disease? or at least to not over call it?


January 16, 2007: Workflow for AMIGO Tumor Ablation Procedures


Present: Stuart Silverman (SGS), Paul Morrison (PRM), Victor Gerbaudo (VG), Angela Kanan (AK), Janice Fairhurst (JF), and George Oliviera (GO).

Reviewed “Workflow” for AMIGO Tumor Ablation Procedures

  • PRM presented an overview of ablation procedures currently performed under MRI and CT. Photos included highlights from a representative CT guided ablation procedure.
  • Briefly reviewed of the “Benefits”, “Challenges” and “Approaches” of PET/CT guided ablation as perceived in 2005/2006 at the outset of discussions on the topic.
  • Reviewed draft of the “Workflow” document itself. Edits were made to Team list, Suite Utilization, Suite Prep & Calibration, Procedure and Other Issues/Needs.
  • Current plan is to circulate the next draft to Team Members for comment, and then forward to N. Hata.



December 19, 2006: Image Subtraction Project


Present: Paul Morrison (PRM), Neculai Archip (NA) and George Oliviera (GO)

Image Subtraction” Research Project -- “Image Subtraction” is currently performed as part of the clinical exam protocol following ablation. A retrospective study of the utility of this image subtraction has been proposed. Today, GO presents a literature review to help define the project’s goals. Highlights of that presentation follow:

  • The literature contains reports on both CT and MRI for the follow-up of ablation. Residual tumor and recurrences are evaluated by looking at the size of the ablation bed and the enhancement patterns.
  • As we think about image subtraction to aid in discerning post-ablation tumor residual/recurrence, we look in the literature for how image subtraction has been used for diagnosis. The issue of image registration (for a valid subtraction) is often understated in the current literature.
  • References reviewed included: Rokfsy (pictorial essay in liver); Kinkel (pelvis, T2w versus subtraction images; image artifacts were rated as good, fair, poor; criteria for good image included clear vessels); Murray (spine, post-surg); Soyer (liver); Other (brain; included 5 point scale).
  • Note: Seung-Schik Yoo in SPL had report (Eur Radiol 2002) on subtraction techniques for diagnosing breast malignancy.

% Project could consider asking: How good are the subtraction images provided by current clinical practice (organ specific issues?)? Higher level question could be (as proposed at the outset) Is there more information in the image subtraction images for ablation assessment.