HEAPHY 1 & 2 DIAGNOSTIC Delia DEPHOFF Fri 30 th Aug 2013 Session 2 / Talk 3 11:22 – 11:33 ABSTRACT Earlier this year Lakes Radiology was approached by Scion in Rotorua about using MRI and CT as part of a research project to assess the amount of water in wood. This paper reviews the process of setting up scan protocols, problems encountered and how they were solved, the significance of using MRI and CT, how the information obtained from the scans has assisted the researchers and what has been learned from this experience.

Delia Dephoff NZIMRT Conference 2013 Hamilton Using MRI and CT for scientific research – one MRT’s experience

Background – who, what and why Trials scans – setting things up Research series – modifications along the way Review – was it of value, and what I learned

 Scion - Crown Research Institute dedicated to improving the international competitiveness of the New Zealand forest industry and building a stronger biobased economy.  Lakes Radiology - TRG Group – private medical imaging facility

Slobodan the researcher Delia the MRT

 Research on different wood drying processes Why CT and MRI?  Non-destructive measurement of the moisture content of wood What was different about this research?  1st time MR &CT used in same research

Kiln dried wood (KD) – dries from the outside – resulting in cracking and warping Dewatered wood (DW) – basically replaces water in wood with alcohol which is then extracted – wood dried quickly from the inside – minimise cracking and warping

 To scan the wood to set scan parameters  To assess the data obtained and determine if the information would be useful for the research.

 Pinus Radiata  100x50x600mm (2 foot 4x2)

Matching their expectations to the capability of the scanners

 Based on extremity scan  Dropped to 80 kVp, eff 50mAs (32mAs)  Kernals – soft tissue (B41s) and Bone (B70s)  2mm slices and 0.75mm slices  Pitch 1.5  16x0.6m  Rotation time 1.5  Scan time 44.75s  CTD I Vol 1.43 mGy

Images - Streaking artefact ?partial volume averaging beam hardening (Seeram, 2001)

 Length of wood vs FOV  Coils – spine coil and body matrix x 2  T1, PD, T2  Scanned a small block  5mm slices

 HUGE amount of data esp CT  Raw data – 2.5GB  Siemens technical help  Transferred data onto external hard drive

1 st series – comparing kiln dried wood to de-watered wood 2 nd series – de-watered wood, Green, 3xDW, 5xDW, 10xDW 3 rd series – unexpected results therefore re- scan after 2xDW and 10xDW

 Wanted whole length of wood scanned  Change parameters slightly  Scan in two blocks, with overlap  Slice 7mm  Scan time approx 5mins each - 6 scans – 30mins to scan each set of wood T1PDT2 TR TE223792

T1PDT2

T1 PD T2 1 st 2 nd

T1PD T2

 Talked and asked questions – resulted in some minor adjustments to the research  Wood processing  Basics of CT and MRI  Hounsfield Units  Kernals – AKA Convolution filters  B41s high frequency filter  B70s low frequency filter (Bushong 2000)  B90s

 Results from 2 nd series not quite as expected  Water content was down after 3 DW, but increased after 5 DW, down again after 10DW  2x DW to 10 x DW  Use alcohol as a reference

T1 PDT2 Green 2DW 10DW

 Yes and no  PD most useful MR scan  Amount of data, especially CT – time to analyse  Unexpected results

 To get everything set on the trial scans, minimise errors, variables – check all parameters match  If there are options (e.g. kernals) give all for analysis  Revise CT and MR physics

 Water content of wood, free water and bound water  Wood drying processes – kiln, dewatering and oven drying  You cannot measure the water content of a wet piece of wood, but you can measure how much water it used to contain once it has been dried.

 Scion Research  Lakes Radiology – TRG Group  Slobodan Bradic

 Bushong, S.C. (2000) Computed tomography. Mc Graw-Hill: New York  Seeram, E. (2001) Computed tomography. Physical principles, clinical applications, and quality control (2 nd ed). Saunders: Philadelphia