MRI-current and future

applications-

Masako KataokaDept. of Diagnostic Imaging and Nuclear MedicineKyoto University Graduate School of Medicine

Abbreviated version: please note that some of the images/slides used in the actual talk were omitted.

2

Morphology Kinetics(vascularity)

UltrafastAbbreviated

Dedicated breast PET(+metabolic info.)

DWI(Cellularity, morphology,

vascularity,structure)

Outline

1. Ultrafast(UF) -DCE MRI2. DWI –recent advancement3. Dedicated breast PET

What is UF-DCE MRI?

Scanning (at very early phase) with high temporal resolution (seconds)& high spatial resolution

Kinetic curve at very early phase

“FAST” scanning tech is needed

Ultrafast (UF)-DCE MRI

injection start

UF-DCEHigh Resolution

CEC-DCE(delay)

C-DCE(initial)

C-DCE(pre)

SI

Sec-60 0 60 120 180 240 300 360

pre+19 frames(every 3.7sec/frame)

-15-75

Parallel imaging 01

View-sharing 02

Compressed sensing 03

Ultrafast (UF)- DCE MRISteeper curve – more likely to be malignant

Mann R et al. Investigative Radiology 2014

Information obtained on UF-DCE MRI is comparable to that obtained by Conventional (C)-DCE MRI. Abe H et al. AJR 2016

Diagnostic performance of UF-DCE =C- DCE

0 2 4 (min.)

Conventional (C) -DCE MRIBI-RADS curve analysis

Ultrafast DCE MRIlook at the early upslope

Artery

Vein

AVI

Artery

Vein

Interval

MS

Slope

TTE

Time

empiric mathematical model (EMM)Mori N, Pineda FD et al. AJR 2018.

Examples of kinetic parameter in UF-DCE MRI

Curve fitting

Maximum Slope (MS)of the contrast enhancement versus time curve

• A parameter of the inflow of contrast in lesions.• How fast/strong the lesions enhance.

• Malignant lesions show steep upslope (large MS). • Equivalent or better diagnostic performance

compared to washout info. from C-DCE MRI

→Time (sec)

type1

type 2

type 3

50° 30°

Rel

ativ

een

hanc

emen

t(%

)

10 15 20 25 30 35 40 45 50 55 60 65 70Time (sec)

Relative enhancement (%)

type 1 → malignanttype 3 → benign

the slope of the tangent (%/s) along the steepest part of the curve

Mann RM et al. Invest Radiol, 2014.Goto M et al. European Radiology 2018.Ohashi A et al. European Journal of Radiology 2019 ( in press)Honda M et al. JMRI 2019 (in press)

Time to enhancement (TTE)

• Malignant lesions start to enhance earlier (shorter TTE) than benign lesions.

0

50

100

150

200

250

10 20 30 40 50 60 70

Aorta LesionTime (sec)

Relative enhancement (%)

Lesion

Aorta

“The time point where the lesion starts to enhance” minus “the time point where the aorta starts to enhance”

• A parameter of the inflow of contrast in lesions.• How early the lesions start to enhance.

• Time of arrival (TOA) similar but more precisely defined

• Bolus arrival time (BAT) : start of injection-bolus arrival at a lesion

Mus RD et al. Eur J Radiol, 2017.Pineda et al. Academic Radiology 2016.Goto M et al. European Radiology 2018.Honda M et al. JMRI 2019 (in press)

7/20frames

AVI = 8 – 7 = 1 frame

Artery

Natsuko Onishi , et al. JMRI. 2017

The time interval between arterial and venous visualization (AVI)

• A parameter to evaluate breast vascularity when arteries and veins are visualized

• Thanks to the compressed sensing technique, detailed peri-tumoral vasculature can be evaluated.

• A-V interval is shorter for malignant lesions than for benign lesions.

“The time point where the breast vein starts to enhance” minus

“the time point where the breast artery starts to enhance”

8/20frames

Vein

Maya Honda, et al. JSMRM 2017

AVI for breasts with cancers were significantly shorter than those for breasts with benign lesions (*P=0.043) and with no lesions (**P=0.007).

Arterial Venous Interval -shorter in cancers

*

Natsuko Onishi. et al. JMRI 45, p617, 2017

Video slide on You Tube “JMRI ISMRM” channel “ultrafast”

usual ductal hyperplasia(benign) Small MS (14.7%/sec)Large TTE(14.5 sec)AVI (3frames~11sec)-s/o benign

Although C-DCE kinetic curve showed washout

Honda M et al. JMRI (Epub 2019)

Benefit & Pitfalls

Benefit

UF-DCEHigh Resolution

CEC-DCE(delay)

C-DCE(initial)

C-DCE(pre)

SI

Sec-60 0 60 120 180 240 300 360-15-75

1.Shorter image acquisitionShorter reading time

(similar to “abbreviated MRI)

2.Easier to identify lesions in case of marked BPE3.Tumor-related artery & vein separation4.Detailed tumor-related vasculature can be evaluated

1. Number of iterations should be optimised

No. of Iteration 1→ 15→ 50

Sagawa H. et al. Magnetic Resonance in Medical science 2018 (Epub)

Invasive carcinoma

Optimal scan setting is required!

2. Compressed sensing: Reconstruction not speedy!3. The same lesion may look different in shape

Pitfalls

Honda M et al. IC-MRI 2019 , Kataoka M et al. ISMRM 2019

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Ultrafast DCE MRI- summary

Shorter scanning timeEarly phase kinetic curve analysis (seconds)New kinetic parameter (MS, TTE, AVI etc..)Useful in Marked BPEVisualize tumor-related vasculature

Outline

1. Ultrafast(UF) -DCE MRI2. DWI –recent advancement3. Dedicated breast PET

DWI-recent advancement“EUSOBI” are actively working on standardizing DWIIncrease in publications related to DWI & Breast

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Figure 5: Summary receiver operating characteristics (SROC) curves by using the bivariate model with 95% confidence regions. Thepooled area under the curve was 0.92 for the apparent diffusion coefficient (ADC), 0.90 for tissue diffusivity (D) and 0.94 for the prime diffusion coefficient (λ1).

Baxter GC et al. Radiology 2019 June

AUC 0.92 AUC 0.9 AUC 0.94

DWI-recent advancement

1. High resolution DWI

2. Non-ADC approach

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Diffusion Weighted Imaging（DWI)Random Brownian motion of water molecules Apparent diffusion coefficient (ADC) : quantified measure of diffusion

DWI

ADC map

Free water no restriction

Cancerrestriction ++

Tissuerestriction +

DWI LOW HIGH

LOWADC HIGH

DWI Signal intensity (SI) and ADC value-Monoexponential model-

b value

ln (SI)

0 500 1000

S(h) = S(0) ･ exp (-bD)ln SI = -bD + lnS0

ADC ~ slope

low ADC (cancer)

high ADC (cyst, FA etc..)

Problem of conventional DWI• Low spatial resolution• Susceptibility artifact-causing distortion• Poor fat suppression

Camp J. BJR 2019

High-resolution DWI for morphological assessment

-various strategies-Reduced FOV DWI

Bogner W et al. (2015), Radiology

Bickelhaupt S et al. (2015), Radiology

Barentsz M et al. (2015), JMRI 42, p1656

DWIBS (DWI + STIR)

Readout-segmented EPI at 7T

Readout-segmented EPI Kim, YJ et al. (2014), KJR 2014 CE vs DWI

Readout segmented EPI(rs-EPI: RESOLVE)

• K-space is divided into segments• Shorter acquisition time per shot• Less distortion (susceptibility artifact ↓）

• 2D navigator echoes for reduced sensitivity to motionDrawback: Longer scanning timePorter DA et al. MRM (2009)Bogner W et al. Radiology (2012)Wisner DJ et al. JMRI (2014)

HR-DCE MRI vs HR-DWI(HR) DCE MRI HR-DWI with Rs EPI

MR Sequense 3D VIBE Three direction traceSequence parameterFlip angle 15 degree b values (sec/mm2)

0, 850 TR/TE (sec) 4.01/1.63 10500/52

In-plane Resolution 0.7x0.6 1.1x1.1Thickness (mm) 0.8 1.5No. of Segments 7

NEX 1 1 and 2 (b=850 sec/mm2)Acquisition time 2min 26 sec 5min 15 sec

HR-DWI using rs-EPIFor known breast cancer-• Agree with DCE-MRI and pathology for mass lesions,

yet sometimes challenging for non-mass lesions• Non-contrast protocol with HR-DWI may work for

those with “suspicious” lesion. Currently limited to unilateral Screening ?

Excellent Excellent Underestimation

DW-MRI –non ADC approach

ADCo KfIVIMCE

IDC

PASH(benign)

Iima, Yano, Kataoka et al. Invest Radiol 2015.

Non-Gaussian parametric map

(b value)

80 500 1000 1500 2000 2500 3000 3500

SI

Iima, Kataoka et al. Radiology 2018

Using all three parameters helps to improve more accurate diagnosis without using contrast agent

IVIM

ADC

Kurtosis

DWI contains various info (multi b value data)- various approach (kurtosis, stretched exponential…)Potential for new biomarkers in oncology

Bedair R. et al. Eur Radiol (2017)

ROCs for the response prediction of the pretreatment diffusion coefficients. DDC (stretched exponential) performed best.Kurtosis (red) and

stretched-exponential (blue) models were best supported by the data

Suo. et al, JMRI (2017)

Beyond ADCIVIM& non Gaussian DWI

Jin YN. et al, JMRI (2019)

parameters derived from the biexponential & stretched-exponential DWI could provide additional information for differentiating between benign and malignant breast tumors

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DWI recent advancement-summary

Morphology can be evaluated Using high-resolution DWI

non-ADC parameters for new biomarkers

0.8-500 500 1500 2500 3500

Outline

1. Ultrafast(UF) -DCE MRI2. DWI –recent advancement3. Dedicated breast PET

Whole body (wb) PET/CT & dedicated breast (db) PET examination flow

185MBq FDG

wbPET

supine

dbPET

prone

60 min 5 min x both sides (2)

90-100 min

0 min

60 min waiting

What is the value of dbPET? Very small pixel size→ decrease partial volume effectMetabolic morphology associated with pathology(intratumoral heterogeneity)Treatment response (residual cancer after NAC)Screening?

Visualize metabolic & morphological info. with better sensitivity.

Female, 40th

Grade 3Triple negative subtypeKi-67 index: 60%

Sakaguchi R et al. Annals of Nuclear Medicine 2019 (E-pub)

What are the benefits for patients in using these “near future” approach?

1) Shorter, less invasive imaging

2) Comprehensive information for optimized /personalized management