TUMOR IMAGING UPDATE | DR DEEPAK PATKAR | MR SPECTROSCOPY

Summary

This talk delves into the transformative evolution of brain tumor imaging over the past decade, highlighting the shift from purely anatomical to advanced functional MRI techniques. It underscores the pivotal role of MRI in pre-surgical planning, treatment response assessment, and differentiation between true progression and pseudo-progression. The lecture explores the practical applications of MR spectroscopy and diffusion tensor imaging in distinguishing benign from malignant tumors, and their impact on surgical and therapeutic strategies. The speaker emphasizes the importance of an integrated, patient-centric approach to imaging, advocating for a shift towards value-based and outcome-focused radiology practices.

Takeaways

• 🧠 Brain tumor imaging has evolved significantly over the last decade and a half, shifting from purely anatomical to incorporating vascular, metabolic, and functional imaging techniques.
• 📈 The use of MRI in diagnosing brain tumors has progressed to include functional imaging, aiding neurosurgeons in planning surgeries with greater precision.
• 🔍 Advanced MRI techniques have enhanced the ability to assess treatment responses, differentiate between true progression and pseudo-progression, and discern true responses from pseudo-responses in patients undergoing chemotherapy or post-surgery treatments.
• 🌐 The conventional MRI sequences have been expanded to include advanced sequences like spectroscopy, diffusion, diffusion tensor imaging, and fusion imaging, providing more detailed insights into tumor characteristics.
• 🧪 MR spectroscopy plays a crucial role in distinguishing malignant from benign brain tumors by analyzing the ratios of various metabolites, aiding in the diagnosis of high-grade tumors and metastasis.
• 🔎 Diffusion and diffusion tensor imaging (DTI) help differentiate high-grade tumors from low-grade ones by measuring the restriction of water molecule movement within the tumor environment.
• 🏥 Practical clinical applications of advanced imaging include better surgical planning, understanding tumor infiltration versus deflection, and assessing white matter tract integrity for treatment strategies.
• 📊 The integration of conventional and advanced imaging techniques provides a comprehensive view of the tumor, aiding in the development of new treatment strategies and improving patient outcomes.
• 🤝 Interspecialty communication and coordination are emphasized as critical for effective patient treatment, highlighting the importance of radiology's role in the patient care continuum.
• 🌟 The future of radiology is envisioned to be both image-centric and patient-centric, with a shift towards value-based imaging and outcome-focused reporting, underlining the need for training future generations in these advanced techniques and values.

Q & A

How has brain tumor imaging evolved over the last decade?

Brain tumor imaging has evolved from pure anatomical imaging to include vascular, metabolic, and functional imaging. This shift has enabled more sophisticated surgical planning and better assessment of treatment responses.

What is the role of MRI in current brain tumor imaging?

MRI plays a crucial role in brain tumor imaging by providing functional imaging capabilities. It allows for the differentiation of true progression from pseudo-progression and true response from pseudo-response, thus aiding in better understanding of tumor behavior.

How does functional MRI benefit neurosurgeons?

Functional MRI benefits neurosurgeons by enabling them to plan surgeries in a more sophisticated manner, assess treatment responses, and differentiate between different types of tumor progression and responses.

What are the newer MRI sequences that have been introduced for brain tumor imaging?

Newer MRI sequences include spectroscopy, diffusion imaging, diffusion tensor imaging, perfusion imaging, arterial spin labeling, and fusion imaging. These sequences provide more detailed information about the tumor and its environment.

What is spectroscopy and how does it help in differentiating brain tumors?

Spectroscopy is a technique that provides information about the chemical composition of tissues. It helps in differentiating malignant brain tumors from benign ones by analyzing the ratios of certain metabolites like choline, creatine, and lipids.

How does diffusion imaging contribute to the assessment of brain tumors?

Diffusion imaging measures the movement of water molecules in tissues. It helps in identifying highly cellular tumors by showing restricted diffusion, which is indicative of areas with high viscosity or dense cell membranes.

What is diffusion tensor imaging (DTI) and its significance in brain tumor imaging?

Diffusion tensor imaging is an extension of diffusion imaging that provides information about the structural connectivity and microscopic axonal organization of white matter tracks. It helps in localizing tumors in relation to these tracks and differentiating infiltration from deflection.

How can MRI spectroscopy differentiate between tumor recurrence and radiation necrosis?

MRI spectroscopy can differentiate between tumor recurrence and radiation necrosis by analyzing the presence of certain metabolites. High choline levels indicate tumor recurrence, while low choline and high lipid peaks suggest radiation necrosis.

What are the practical clinical applications of DTI in brain tumor imaging?

DTI has practical clinical applications such as track-specific localization of tumors, differentiating tumor infiltration from deflection, aiding in neurosurgical planning, and detecting white matter invasion by tumors.

How does the integration of conventional and advanced imaging techniques impact the understanding of brain tumors?

The integration of conventional and advanced imaging techniques provides more detailed information about the underlying pathology of brain tumors. This aids in improving the understanding of brain tumors and helps in the development of new treatment strategies.

What is the importance of being both image-centric and patient-centric in radiology?

Being both image-centric and patient-centric in radiology ensures that radiologists focus not only on the imaging details but also on the patient's overall treatment. This approach promotes interspecialty communication and coordination, leading to more value-based imaging and outcome-focused reporting.

Outlines

00:00

🧠 Evolution of Brain Tumor Imaging

The speaker outlines the significant advancements in brain tumor imaging over the past decade and a half, highlighting the transition from purely anatomical imaging to a more comprehensive approach that includes vascular, metabolic, and functional imaging. The role of MRI has evolved to enable neurosurgeons to plan surgeries with greater sophistication, assess treatment responses, and differentiate between true progression and pseudo-progression in patients undergoing chemotherapy or post-surgery treatments. The speaker emphasizes the importance of multiparametric MRI parameters in understanding tumor behavior and the shift from conventional sequences to advanced techniques like spectroscopy, diffusion, and perfusion imaging. The integration of functional and structural imaging provides a more complete picture, aiding medical teams in tumor grading, characterization, and localization, as well as in planning treatments and assessing responses.

05:01

🧪 Applications of MR Spectroscopy in Tumor Diagnosis

The speaker delves into the practical applications of MR spectroscopy in distinguishing between malignant and benign brain tumors. It discusses the use of specific metabolite ratios, such as choline, creatine, and lipids, to identify high-grade tumors and metastasis. The practical utility of MR spectroscopy is exemplified through its ability to differentiate between tumors and radiation necrosis, cystic tumors and abscesses, and various types of brain lesions. The speaker provides concrete examples of how spectroscopy can help in clinical settings, such as differentiating glioma from metastasis based on the presence of specific metabolites. The discussion also touches on the differentiation of lymphoma from other entities by the presence of a 'quin' peak sign and the identification of oligodendroglioma through its unique spectroscopic signature.

10:03

🔍 Role of Diffusion and Diffusion Tensor Imaging (DTI) in Tumor Characterization

The speaker explains the principles of diffusion and diffusion tensor imaging (DTI), which measure the free motion of water molecules in the brain's intra and extracellular compartments. These techniques are used to identify highly viscous or membrane-bound lesions, such as abscesses and highly cellular tumors, which exhibit restricted diffusion. The speaker references a 2006 article to discuss how diffusivity can differentiate high-grade tumors from low-grade ones. DTI's clinical applications include the localization of tumors in relation to white matter tracts, differentiation of tumor infiltration from deflection, and planning for neurosurgical procedures. The speaker provides examples of how DTI can be used to distinguish between different types of brain tumors based on the pattern of tract disruption or displacement, which is crucial for treatment planning and understanding tumor behavior.

Keywords

💡Brain Tumor Imaging

Brain tumor imaging refers to the use of various medical imaging techniques to visualize brain tumors. In the video, it is discussed how this field has evolved from purely anatomical imaging to include vascular, metabolic, and functional imaging. This advancement allows for more sophisticated surgical planning and better assessment of treatment responses, as highlighted by the speaker's mention of how MRI has progressed to include multiparametric parameters.

💡MRI (Magnetic Resonance Imaging)

MRI is a non-invasive imaging technique that uses strong magnetic fields and radio waves to create detailed images of the body's internal structures. The video emphasizes the evolution of MRI's role in brain tumor imaging, moving from basic anatomical imaging to more advanced functional imaging, which aids in treatment planning and response assessment. The speaker notes the transition from simple sequences to advanced ones like spectroscopy and diffusion imaging.

💡Multiparametric Imaging

Multiparametric imaging refers to the use of multiple imaging techniques or parameters to obtain a comprehensive view of a medical condition. The video discusses how multiparametric MRI parameters have become integral in understanding brain tumors better, providing insights into tumor behavior and aiding in treatment response evaluation.

💡Functional Imaging

Functional imaging is a type of medical imaging that measures and maps the brain's function. The video explains how functional MRI has become crucial in brain tumor imaging, allowing for the differentiation between true progression and pseudo-progression of tumors, and between true and pseudo responses to treatment.

💡Spectroscopy

Magnetic resonance spectroscopy (MRS) is a technique that provides information about the chemical composition of tissues. In the context of the video, spectroscopy is highlighted as a key tool in differentiating malignant from benign brain tumors by analyzing the ratios of certain metabolites, such as choline and creatine.

💡Diffusion Imaging

Diffusion imaging, specifically diffusion-weighted imaging (DWI), measures the movement of water molecules in tissues. The video explains how restricted diffusion is indicative of highly cellular tumors, which is used to differentiate high-grade tumors from low-grade ones. It is also used to differentiate abscesses and cystic tumors.

💡Diffusion Tensor Imaging (DTI)

DTI is an advanced form of diffusion imaging that assesses the structural connectivity of the brain by examining the microscopic organization of white matter tracts. The video describes how DTI helps in localizing tumors in relation to white matter tracts, differentiating tumor infiltration from deflection, and planning neurosurgical procedures.

💡Pseudo-progression

Pseudo-progression refers to an apparent increase in tumor size on imaging studies that is not due to tumor growth but rather treatment effects. The video discusses the importance of functional imaging in distinguishing pseudo-progression from true tumor progression, which is crucial for proper treatment planning.

💡Perfusion Imaging

Perfusion imaging assesses the blood flow within tissues, providing information about vascularity. Although not explicitly detailed in the provided script, perfusion imaging is mentioned as one of the advanced sequences in MRI that contribute to the functional information about brain tumors.

💡Fusion Imaging

Fusion imaging involves combining data from different imaging modalities to create a single, comprehensive image. The video script mentions fusion imaging as a part of the advanced MRI sequences that, when combined with other techniques, provides a more detailed understanding of brain tumors.

💡Interspecialty Communication

Interspecialty communication refers to the exchange of information and collaboration between different medical specialties. The video emphasizes the importance of this communication for a comprehensive understanding of patient conditions and effective treatment planning, particularly in the context of brain tumor imaging.

Highlights

Imaging of brain tumors has evolved from pure anatomical imaging to vascular, metabolic, and functional imaging.

MRI's role has progressed from anatomical to functional imaging, aiding in sophisticated surgical planning.

MRI is effective in assessing treatment response, differentiating true progression from pseudo-progression.

Advances in brain tumor imaging have led to a better understanding of tumor behavior by medical professionals.

Conventional MRI sequences have been enhanced with new advanced sequences like spectroscopy, diffusion, and perfusion imaging.

Functional and structural imaging combined provides comprehensive information for medical teams.

New MRI sequences offer unique insights for tumor grading, characterization, and localization.

MR spectroscopy helps differentiate malignant from benign brain tumors based on metabolite ratios.

Practical applications of MR spectroscopy include distinguishing tumor types and complications like radiation necrosis.

Diffusion and diffusion tensor imaging (DTI) aid in differentiating high-grade tumors from low-grade ones.

DTI allows for track-specific localization of tumors and differentiation of infiltration from deflection.

Integration of conventional and advanced imaging techniques provides detailed pathology information.

Radiology must be both image-centric and patient-centric, focusing on interspecialty communication and coordination.

The future of radiology aims for value-based imaging and outcome-focused reporting.

The responsibility of training future radiologists includes advancing knowledge and emphasizing patient care values.

Transcripts

what i'll be doing in next 15 minutes

is talking about how imaging of brain

tumors

have changed over last decade also and

what is the current status

of role of mri including its

multiparametric parameters

in terms of the current status

there have been several advances in

brain tumor imaging over the last

decade decade and a half the

brain tumor imaging has changed

completely from

pure anatomical imaging to vascular

metabolic and functional imaging

use of mri as a diagnostic tool has

progressed from

completely anatomical imaging to

functional imaging

this allows neurosurgeons to plan

surgeries in a very sophisticated manner

it is effective in assessing treatment

response

when you are giving chemo or regulatory

post surgery

it differentiates true progression from

pseudo progression

and it also differentiates true response

from

pseudo response and this has allowed

the oncologist radiation oncologists and

surgeons

to understand the tumor behavior

much better it also allows a good

detection and assessment of

what is going to happen to the patient

in a much

sophisticated manner so the

routine conventional sequences in

human imaging in central nervous system

has moved from simple spin echo sequence

gradient echo sequence fast clinical

sequence inversion recovery sequence

flare sequence to a lot of new basic and

advanced sequences

in terms of a mass spectroscopy

diffusion

and diffusion tensor imaging or fusion

imaging

artillery spin leveling which is a part

of perfusion imaging without having

to inject contrast the true functional

imaging

which is bold imaging and fusion imaging

when these functional and structural

imaging

is combined together it gives

a complete information this allows

the medical oncologist surgical team

and radiation oncologist greater

insights into grading of humor

characterization of tumor functional and

anatomical localization of tumor

it also allows better understanding of

secondary effects on the adjoining white

matter tracks

helical cortexes etc it allows better

operating planning

response to treatment as i said solar

response or true response

and it allows much more accurate

information about

whether there is a recurrence of the

tumor or there are post

treatment changes so human protocol has

changed completely

from just a simple imaging to function

imaging and that's what we are going to

understand

in next 15 minutes so each of these new

sequences

provide very unique information which

when combined together

has implications for defining

the tumor type and grid better directing

biopsy

or surgical resection better planning

radiation and biological therapies

in a much accurate way it also assesses

the treatment response much earlier

quicker

and better than what we were doing

before and it also

allows the researchers understanding

mechanism of success and failure

of newer treatments typically

anti-angiogenesis therapy

so what are the newer sequences in

mri that allow this functional

information is better so you have

spectroscopy

difficult tension imaging perfusion

imaging arterial spring lending

functional mri and fusion imaging in

this part of the lecture we are going to

cover only spectroscopy

and diffusion and diffusion tensor

imaging and in the next part we are

going to cover

the other four sequences so let's start

with

understanding spectroscopy and

its role in differentiating malevolent

brain tumors

from benign ones there is a lot of data

available

across literature but what is by and

large followed

is this meta-analysis

covered by agnr in 2006

which talks about higher ratios of

coding upon creatine

with cutoff of two coding upon na

with cutoff of 2.2 and choline plus

gradient

upon mn and creating upon na

to decide that you are living with a

hygrid tumor

lower ratios of lipid upon lactate and

creatine upon lactate

is also considered as a patient

suffering from high grade tumor

metastasis can be differentiated from

hybrid lemons

by presence of high lipid gradient ratio

so what are the practical applications

of mr spectroscopy

it distinguishes abnormalities with same

imaging appearances and the examples are

differentiating tumor from radiation

necrosis

differentiating cystic tumor from

abscess differentiating metastasis

from astrocytoma or biomass

and differentiating toxoplasma from

lymphoma

when patient is immunocompromised and

here are actual examples

so these two morphologically

look quite similar although the size is

different

and it will be virtually impossible to

differentiate glioma

from metastasis then look at

spectroscopy so if we have

presence of mi and presence

of creatine that indicates

that you are dealing with drama also

in the peritumoric area what looks like

edema

if you have presence of choline that

indicates

your delay with an astrocytoma or

glycoma

metastasis on other hand will have

complete absence of intra-tumor

choline as well as intra-tumor

mi it will show lot of

lipid which will be absent in glioma so

that is the way to differentiate

glioma or primary tumors of brain

versus metastasis lymphoma can be

differentiated from these two entities

by presence of what is called as queen

peak sign

so when you have two top peaks of lipid

lactate

and choline you know you are dealing

with lymphoma oligodendroclima

on the other hand will have relatively

low cooling

high creatine and high in my

glycine so it's impossible to

differentiate glycine from

mi because both resonate

at the same location also if you

add the presence of tumor mainly in gray

matter

with infinite pattern you know you are

dealing with oligodendroplasma

and not astrocytoma or glioblastoma

radiation necrosis can be differentiated

from

recurrence of a tumor by

tall lip electric peak from 0.9

to 1.3 ppm with relatively

low cooling so when you have

post tumor bed evaluation

you want to differentiate recurrence of

a tumor from radiation necrosis

run a multivoxel spectroscopy

and look for in the tumor bed presence

of high choline

that would indicate presence of

recurrence

if across all the box cells there is

only

high level and nothing else you know you

are dealing with

radiation necrosis so relation necrosis

will have low cooling

high liquid tumor recurrence will have

high choline

and high choline in a ratio so that is

about

role of mr spectroscopy in

brain tumor imaging let's now move on

and see how diffusion and diffusion

tensor imaging

helps us in differentiating high grade

biomass

from road grid rhymers or any other

entities

how does diffusion work it is basically

an index of free motion

of water in the intra and extracellular

compartment

of the brain cells anything that has

high viscosity

or high membrane would impede motion and

then

will show a restricted diffusion so any

lesion with high similarity

so we are talking about hydrogen we have

restricted diffusion

anything that contains pus so we are

typically talking about abscess

which show restricted diffusion so

restricted diffusion will be seen in

abscesses

and highly cellular that means hydrate

tumors

based on this again the same article of

agnr in 2006

allows us to talk about differentiating

hybrid lamas

from low grade glamours by looking at

diffusivity

so hydrograms will show lot of

restricted

diffusion low grade lemons will show

facilitation of diffusion intermediate

grid glimmers will show

relatively less restricted diffusion

abscesses which show restricted

diffusion in the center

whereas if it was a cystic tumor the

solid component or peripheral component

of the cystic fibroid would show

restricted fusion

diffusion tensor imaging is an extension

of diffusion sequence a non-invasive way

of

understanding brain structural

connectivity it also allows us to look

at

microscopic axonal organization of white

metal tracks

and based on the directional rate of

diffusion of water molecules

we can see where the diffusion is

facilitated more

and where it is not so little bit of

more understanding

of diffusion tensor imaging

when we say that hydrogen atoms in

the entrance of the compartments are

flowing

at a rate of five centimeters per minute

that's not a complete proof

so along the white metal tracks the

water molecules

are moving at five centimeters per

minute

perpendicular to it the diffusivity is

virtually

zero and what we see in tumors and in

the region

is something in between so we calculate

fractional anisotropy

and look at how the diffusion is

so whenever diffusion is maximum you

will see

more restricted diffusion that is in

hybrid tumors

and when it is lesser you will see

facilitation of diffusion

that is called as fa and based

on the fractional anisotropy tracts

which are in transverse axis are labeled

as red

those superior interior are labeled as

blue and those enteroposterior are

labeled as green

and color used depends on the intensity

of fa what are the practical clinical

applications of dti

it allows track specific localization of

environmental

agents it allows localization of tumors

in relation to white metal tracts

it differentiates infiltration from

deflection and that is important

in grading the tumors it allows

localization of

male vitamin tracks for neurosurgical

planning

and it also detects awkward white matter

invasion

by hybrid life so based on the pattern

of dti you can actually decide

which tumor you are dealing with for

example

in gland mass and metastasis the tracks

will be displaced

whereas in anaplastic astrocytoma and

gbms

the tracks will be infiltrated but they

will remain

identifiable in very high grade

anabolistic astrocytomines and galliums

tracks will be completely disrupted

whereas in metastasis

and in edema the tracks will be normal

but just

displaced with slight change in the

color view and these are the actual

example this is a

left frontal lobe polygon

the tracks here are displaced but not

infiltrated

compare that with another quantum

learner which is a logarithmic again the

tracks are displaced

and not inverted compare these two

patients with this patient of

the one that i showed you before a

glioblastoma multiforme

in left temporal lobe the tracks are

completely

destroyed here is another example of the

net

in the left posterior frontal cortex the

tracks are displaced

color views are slightly changed but

there is no infiltration

so that is the importance of diffusion

and diffusion tension imaging

in advanced tumor imaging perfusion

attachment leveling functional mri and

fusion imaging will cover

in the next stop so to conclude this

part of the talk

with integration of conventional and

advanced imaging techniques we can

provide

increasingly detailed information about

the underlying pathology

these details will aid in improving our

understanding of brain tumors

and help in development of new treatment

strategies

in future what we also need to

understand

is radiology has to be both image

centric and patient-centric

we must understand that we are an

important

and an integral part of patient

treatment interspecialty communication

coordination is most important

and we must aim to change from volume

based to value-based imaging

from interpretation focus to outcome

focus reporting

and the responsibility of training our

future generation

with not only the advances but these

values lies with us

thank you for your attention

[Music]

you