Three Dimensional Internal Structure Analysis Using Magnetic Resonance Image Data

Of Agricultural Products

Myoung Ho Kim, Seong Min Kim*

Department of Bioindustrial Machinery Engineering, Chonbuk National University, Jeonju 54896, Republic of Korea. smkim@jbnu.ac.kr

Abstract: Magnetic resonance imaging (MRI) system

is widely used as a diagnostic tool in medical areas

recently. MRI technique is a three-dimensional

technology (3D) originally. It provides series of two-

dimensional (2D) image data but users usually utilize

them as 2D image data to get internal information of

objects. Agricultural products having high water

content are good examples for utilizing an MRI

technique. The objectives of this study are to develop a

3D visualization technique using MRI data, and to

monitor the internal structure changes of intact kiwi

fruits due to storage time variation and to investigate

the internal structure changes of intact cherry tomato

fruits with six different growth stages in 3D space.

We used a 1 Tesla industrial grade MRI system with a

permanent magnet to acquire magnetic resonance (MR)

image data sets of target fruits nondestructively. Kiwi

fruits with different storage times and cherry tomatoes

with six different growth stages were investigated.

‘Gradient Echo’ pulse sequence was used to acquire 3D

data sets of intact fruits in the study.

Three dimensional visualization technique suitable for

analyzing series of 2D MR images was developed to

characterize and quantify internal structure of intact

fruits. In the kiwi experiment, samples were stored at

17 oC with 50% RH condition for 19 days and

monitored during the storage. Internal tissue

breakdowns were observed with an increasing storing

period. In the cherry tomato experiment, MR images of

samples with different growth stages from green to red

were acquired and the data sets were analyzed. We

found the internal structural change from the pericarp

area observed clearly from the 3D analysis.

This study suggested that MRI with 3D image analysis

is a powerful method to investigate the internal

structure change of intact agricultural products

nondestructively. This technique could be applied to all

agricultural products.

Key Words: Magnetic Resonance Imaging, 3D

Visualization, Internal Structure, Cherry tomato, Kiwi

fruit

MRI: 1 T Permanent magnet w/ 80 mm coil

Imaging pulse sequence: 3D Gradient Echo

In the cherry tomato experiments, tomato samples with

six different growth stages from green to red were

imaged and the data sets acquired were analyzed. The

internal structure changes with varying growth stages

were investigated. Especially, the signal change from the

pericarp area observed clearly.

In the kiwi experiments, kiwi fruits were stored for 19

days and monitored the internal structure changes with

an MRI system. Internal tissue breakdowns were

observed with an increasing storage time.

This study showed that MRI technique is a very

powerful tool to examine the internal structure of most of

agricultural products nondestructively. The technique

could be applied to most of agricultural products to

monitor the internal physical changes due to external

impact, defects, growth stage change, storing period etc.

ABSTRACTMATERIALS & METHODS

CONCLUSIONS

RESULTS & DISCUSSIONS

Materials

MRI System and Imaging Pulse Sequence

To develop a 3D visualization technique for MRI

data using a isosurface function

To monitor the internal structure changes of intact

kiwi fruits during storage for 19 days in 3D space

To investigate the internal structure changes of

intact cherry tomatoes harvested at six different

growth stages in 3D space

Samples: Cherry tomatoes, Kiwi fruits

Kiwi fruits: stored 19 days at 17 oC with 38%

RH condition

Cherry Tomatoes: harvested at six different

growth stages from green to red

3D Visualization Program: MATLAB(R2017a)

INTRODUCTION

Magnetic Resonance Imaging (MRI)

Objectives

MRI signal sources

Protons and Rate of signal decay

Location and concentration of target

molecules

Sample

Parameter

Cherry

Tomatoes

Kiwi

Fruits

TR (ms)

TE (ms)

Slice Thickness (mm)

Field of View (mm x mm)

Image size (pixels)

40

15

1

50 x 50

256 x 256

50

4

1

80 x 80

256 x 256

ACKNOWLEDGEMENTThis paper was supported by research funds of Chonbuk

National University in 2018.

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Figure. Schematic diagram of MRI system showing

imaging plane and direction.

coronal

sagittal

axial

imaging

coil

sample

magnet &

gradient coil

3D Visualization of MR Image Data

Original 2D MR images → Masked 2D MR images

of Target → 3D visualization of target

Figure. Process of 3D visualization of MR images. Stacked plot

of original MR slice images(left), stacked plot of masked target

MR images(middle), 3 D subvolume plot of target MR

images(right).

Cherry Tomato Experiment

Figure. 3D subvolume plots of cherry tomatoes acquired at

green(top), turning(middle) and red(bottom) maturity stages.

The internal structure changes with different growth

stages were investigated in 3D space

Generally, pericarp and endocarp areas clearly are

distinguished at green growth stage but they are not

separated at red growth stage

At green growth stage, the inner and outer pericarp

regions are separated clearly and outer region

contains more water than inner region

Locule areas are well developed from turning stage

However, water content distributes evenly from

breaker to light red growth stage

MR signal intensity change regarding to different

growth stages are observed in 3D space

Especially, the signal intensity change from the

pericarp area observed clearly

Kiwi Fruit Experiment

The internal structure changes with varying storage

periods were monitored in 3D space

Internal tissue breakdowns were observed with an

increasing storage period in 3D space

Figure. Series of 2D MR slice images(top) and 3D subvolume

plots of a kiwi fruit taken at 19th day of storage.

Figure. Series of 2D MR slice images(top) and 3D subvolume

plots of a kiwi fruit taken at 5th day of storage.