Fundamental Imaging Characteristics and

Resolution of Metal Alloys

By

Marc G. Apple, M.D.

Mark Michael

FWM’s Mission Statement

Fort Wayne Metals was founded and continues to grow because of our dedication to the medical device field

“Our mission is to continuously improve the quality of our products, the speed and efficiency with which we respond to our customers requests, and the knowledge of the materials we work with and recommend.”

Typical Wire Application Need

DiameterStrengthFatigueCorrosion ResistanceElectrical ResistanceFormability

But Now…

Imaging

What size wire should I use?Which alloy will work best?Will flat wire be better than round?How can we find answers?

– What modality will you use?– What is a good image?– What technology will be used?

Where did we start

Most implantable wires lose imaging capability under .004”(.1mm)

The best still perform around .001”(.025mm)

The Concept

Choose wire diameters from .001” to .011” (.025mm to .28mm)

Choose common alloys and candidate alloys

Mount in stable fashionCharacterize using common

modalities

Wire Diameters#100 #50 #25 #20 #15 #10 #5 #4 #3 #2 #1 .25 .18 .127 .114 .098 .080 .057 .051 .044 .036 .025.0100 .0071 .0050 .0045 .0040 .0032 .0023 .0020 .0017 .0014 .0010(100x) (50x) (25x) (20x) (15x) (10x) (5x) (4x) (3x) (2x) (1x)

90 Pt 10 Ni

Candidate Alloys and Materials

MP35NCommercially Pure TitaniumTantalumNitinolPlatinum-10 NiDBS(7)MP-DFT® 28AgConi-DFT® 33Pt

Candidate Alloys and Materials

304V316LVMGoldPlatinumL605Custom 455

Selecting Modalities

Dr. Marc Apple at Parkview Oncology Center

Discuss imaging from a clinician point of view

Choose common modalities: Ximatron Hi-Res FluoroscopyPicker PQS CT Scanning SimulatorSiemans Magnetic Resonance Imaging

Ximatron Hi-Res Fluoroscopy100 cm source to surface distance110kv; 25ma; 3mas, 1.5mag latitude for technician

Typical Fluoroscopic Image

Ximatron Image Comparison

Tantalum

90 Pt-10Ni

Coni-DFT®

-33Pt

MP-DFT®

-28Ag

MP35N

DBS(7)

Nitinol

CP Titanium

Bolus Air

Clinician Comments

Amazed at variation due to equipment set up

Observed “zebra stripe effect” in bird’s eye view

Picker “PQS” System “CT Scan”

130kv; 150ma; pitch=1.5

latitude for technician

CT scan Image Reconstruction Options

Name Windows Level Map Type Description K#

Default 300 40 Ramp Simple Default 0

Lung 1 600 -300 Ramp Simple Scanner 5

Lung 2 120 -650 Ramp Simple Scanner 6

Modified head bone

2516 258 Ramp Simple Scanner 1

Normal Bone

0 210 Step Simple DRR 43

Fat 150 -100 Boxcar Simple 3-D 23

Chest 1060 -900 Ramp Simple 2-D/MPR 21

CT Scan of Wire FrameThanks toKatie Shively, R.T.T.Parkview HospitalRegional Cancer CenterFort Wayne, Indiana

Picker Image Comparison

Variables in Imaging

Media- Impact of bolus was significant

Default equipment settings

Siemens “Magnetom Harmony” magnetic resonance imaging

MRI Measurement Parameters

“Magnetom Harmony” Class1.0 Tesla magnetic fieldOperated at a 42 M#2 frequencyUsed head coil with IR=415.015 internal slices with 3-D reconst3.00mm slice thickness, 0 skip192 x 256 matrixContrast setting W=792-798, C=369-376All images obtained using T-1 weighting

Typical MRI Image

MRI Comparison

Variables in Imaging

Head coil was necessary to obtain images

Resolution was better than presented images

Next Step Options

Explore impact of form on imaging (flat wire, strand, cable, shapes)

Explore surface condition impact (plating, oxides, textures)

Move on to other Modalities (Ultrasound)

Conclusions

Novel pilot study to preemptively evaluate tissue equivalent characteristics before prototype devices

This protocol may prove useful as reference data for diameter and material selection