Nuclear Imaging Modalities for Cardiac Amyloidosis

Flashcards on key vocabulary and concepts related to nuclear imaging modalities for cardiac amyloidosis.

Amyloidosis

A heterogeneous group of diseases characterized by the deposition of insoluble extracellular fibrillary proteins in the heart and other organs.

Cardiac Amyloidosis

The deposition of insoluble amyloid fibrils in the myocardium, leading to restrictive cardiomyopathy and heart failure.

Scintigraphy

A noninvasive imaging method used to diagnose cardiac amyloidosis and evaluate disease burden.

Endomyocardial Biopsy (EMB)

The gold standard procedure for the definitive diagnosis of cardiac amyloidosis.

ATTRm Amyloidosis occurs

in an autosomal dominant fashion

ATTRm amyloidosis leads to

familial amyloidotic cardiomyopathy (FAC) or familial amyloidotic polyneuropathy (FAP)

What is the exact prevalence of FAC

unknown the exact prevalence of FAC but pooled data shows up to 3.9% of African Americans are heterozygous carriers of the amyloidogenic allele, V122I, resulting in cardiac amyloid in an age-dependent penetrant manner.

what is ATTRwt cardiomyopathy (wild type transthyretin amyloidosis)

is underdiagnosed and has been shown to have a prevalence similar to autopsy studies with as many as 30% of patients with HFpEF ≥ 75 years

what causes primary AL amyloidosis (light chain)

deposition of monoclonal immunoglobulin light chains and is associated with plasma cell dyscrasias

What is the most frequently diagnosed amyloidosis

Primary AL amyloidosis

Tc-DPD mechanism

A bone-seeking radiotracer used for identifying cardiac amyloid deposition.

Tc-PYP mechanism

A bone-seeking radiotracer that distinguishes AL amyloid from ATTR amyloid, showing high sensitivity.

123I-MIBG

An imaging agent used to evaluate cardiac sympathetic innervation in heart failure patients with class II or class III and left ventricular ejection fraction <35%.

Does MIBG undergoes enzymatic degradation

yes

Metaiodobenzylguanidine (MIBG) is an analog to what

norepinephrine

what do MIBG and norepinephrine have in common

similar uptake and storage in sympathetic nerve endings

When I231 is coupled with MIBG what is possible

evaluation of cardiac sympathetic function

18F-Fluorbetapir

An FDA-approved tracer for imaging β-amyloid plaques, currently being studied for cardiac amyloidosis.

Myocardial Uptake Patterns

Categories that include absent, focal, diffuse, or focal on diffuse uptake of radiotracers in cardiac imaging.

Amyloid can infiltrate the heart resulting in what

restrictive cardiomyopathy, heart failure, and atrial and ventricular arrhythmias

True or False: planar or SPECT can be used for amyloid image

true

are there approved cardiac amyloid tracers

no

what does cardiac amyloidosis invlove

deposition of insoluble fibrils in the myocardium and is an underdiagnosed cause of heart failure with preserved ejection fraction (HFpEF).

What are the most clinically relevant cardiac involvement occurs in what

primary light-chain (AL) amyloidosis

familial transthyretin amyloidosis (mutant transthyretin, ATTRm)

senile transthyretin amyloidosis (wild-type transthyretin, ATTRwt)

Other forms of systemic amyloidosis including secondary AA amyloidosis rarely affect the heart

What do nuclear imaging modalities for cardiac amyloid allow for

for noninvasive identification of myocardial involvement

differentiating amyloid subtypes

monitoring disease burden, disease progression, and potential response to therapy

After diagnosis for cardiac amyloid what is done

additional testing with immunohistochemistry and/or sequence analysis by mass spectroscopy can identify the precursor protein.

What are some complication form EMB (endomyocardial biopsy)

include arrhythmia

perforation with pericardial tamponade

accidental arterial puncture

pneumothorax

What is the percent of EMB complication

6%

The prognosis of AL amyloidosis is related to what

the number and severity of organs involved with cardiac involvement carrying the worst prognosis

What is more progressive AL cardiac amyloidosis, ATTRm or ATTRwt

AL cardiac amyloidosis

What are the advantage of Tc-DPD

distinguish Al from ATTR amyloid

most useful at extremes of spectrum (intense uptake or absent uptake)

what are the disadvantage of Tc-DPD

not available in the US market

intermediate myocardial uptake concluded to be indeterminate significance

not useful for AL amyloid

What is the imaging modality for Tc-DPD

planer or SPECT

What is the sensitivity for Tc-DPD

100%

What is the specificity for Tc-DPD

88%

What are the advantage of Tc-PYP

potentially distinguish AL from ATTR amyloid

what are the disadvanages of Tc-PYP

limited number of studies validating use

not useful in Al amyloid

what is the sensitiivity of Tc-PYP

97%

what is the specificity of Tc-PYP

100%

what imaging modality is used for Tc-PYP

planar or SPECT

What is the mechanism for 11C-PIB

amyloid deposits

what are the advances for 11C-PIB

currently experimental and further studies warranted

what are the disadvantages of 11C-PIB

more studies needed to validate used

short half life requiring on site cyclotron and limiting use to specialized centers

What image modality is used for 11C-PIB

PET/CT

what is the mechanism of 18F-florbetaplr

amyloid deposits

what are the advantages of 18F-florbetaplr

FDA approved for identifying amyloid plaques in the brain high affinity and specificity for B-amyloid

what are the disadvantages of 18F-florbetaplr

fole in cardiac amyloidosis not established and currently in trail

what is the imaging modality used for 18F-florbetaplr

PET/CT

does this image show negative or positive uptake

negative

does this image show negative or positive uptake

positive

True or False: 99m Tc-PYP is readily available

true

99m Tc-PYP is available as what

unit doses from commercial radiopharmaceutical distributors or as kits for preparation

what is the total body effective does for 99m Tc-PYP

15mCi or 3.2mSv

99m Tc-PYP kits contain - or - single use vails

5 or 30

99m Tc-PYP kits are approved for

bone

cardiac (for the detection of myocardial infarction)

blood pool (radionuclide ventriculography and GI bleeding)

how much ml are in each vail for 99m Tc-PYP

10ml

99m Tc-PYP vails contain —- mg of sodium pyrophosphate and —- mg of stannous chloride and —- mg of total tin

11.9mg

3.2mg

4.4mg

is there test preparation required

no

what images are reconstructed and reviewed in standard cardiac imaging planes using commercial software

anterior and lateral planar images

rotating projection images

reconstructed SPECT images

how are myocardial 99m Tc-PYP uptake patterns categorized

absent, focal, diffuse or focal on diffuse

scans with focal 99m Tc-PYP uptake could represent what

rib fracture or previous myocardial infraction

after myocardial infraction, how long will myocardial 99m Tc-PYP uptake be positive for

7 days

What are the two approaches to quantification

quantitative

semi-quantitative

what is the quantitative approach

myocardial to contralateral lung ratio of uptake at 1 hour

the quantitative approach includes what

Circular target regions of interest (ROI) are drawn over the heart on the planar images and are mirrored over the contralateral chest to account for background and ribs (see Figure 1)

Total and absolute mean counts are measured in each ROI. A heart to contralateral (H/CL) ratio is calculated as the fraction of heart ROI mean counts to contralateral chest ROI mean counts.

for quantitative approach H/CL ratios > 1.5 at one hour indicate what

ATTR positive

or quantitative approach H/CL ratios <1.5 indicate what

ATTR negative

what is semi quantitative

visual comparison to bone(rib) uptake at 3 hours

how is cardiac uptake of 99m Tc-PYP evaluated

semiquantitative visual scoring method in relation to bone uptake

visual scores greater than or equal to 2 on planar or SPECT images at 3 hours indicate what

ATTR positive

scores less than 2 indicate what

ATTR negative

grade 2-3 or H/CL > 1.5 uptake suggest what

ATTR amyloidosis

any degree of 99mTc-PYP uptake can also be seen in AL amyloidosis, and as such a complete evaluation is warranted to exclude this diagnosis.

Semi quantitative visual grading of myocardial 99m Tc-PYP uptake by comparison to bone (rib) uptake grade 0 indicates what

no uptake and normal bone uptake

Semi quantitative visual grading of myocardial 99m Tc-PYP uptake by comparison to bone (rib) uptake grade 1 indicates what

uptake less than rib uptake

Semi quantitative visual grading of myocardial 99m Tc-PYP uptake by comparison to bone (rib) uptake grade 2 indicates what

uptake equal to rib uptake

Semi quantitative visual grading of myocardial 99m Tc-PYP uptake by comparison to bone (rib) uptake grade 3 indicates what

uptake greater than rib uptake with mild/absent rib uptake

what quantifying method was used in this image

quantitation of cardiac 99m Tc-PYP uptake using heart to contralateral lung (h/CL) ratio

what quantifying method was used in this image

grading 99m Tc PYP uptake on planar and SPECT images

What is the patient preparation using 99m Tc-PYP

none

what scan is being done using 99m Tc-PYP

rest scan

what is the dose for 99m Tc-PYP

10-20mCi intravenously

what is the recommended time between injection and acquisition using 99m Tc-PYP

1 hour for SPECT and planar

3 hour SPECT and planar optional

what is the field of view for 99m Tc-PYP

recommended: cardiac or chest

optional: whole body planar

imaging type for 99m Tc-PYP

cardiac or chest SPECT and planar imaging

patient position for 99m Tc-PYP

supine

what is the energy window for 99m Tc-PYP

140keV, 15-20%

what collimator is used for 99m Tc-PYP

low energy, high resolution

what is the matrix size for 99m Tc-PYP

64×64

what is the pixel size for 99m Tc-PYP

3.5-6.5mm

what views are being taken using 99m Tc-PYP for planar

anterior. lateral, and left anterior oblique

what is the detector configuration for 99m Tc-PYP planar images

90 degrees

image duration (number of counts) for 99m Tc-PYP planar images

750,000 counts

what is the magnification for 99m Tc-PYP planar images

1.46

what is the angular range for 99m Tc-PYP SPECT imaging

360 degrees

what is the detector configuration for 99m Tc-PYP SPECT imaging

189 dregrees

what is the ECG gating for 99m Tc-PYP SPECT imaging

off: nongated imaging

number of views/detector for 99m Tc-PYP SPECT imaigng

40

time per stop for r99m Tc-PYP SPECT imaging

20 seconds

what is the magnification for 99m Tc-PYP SPECT imaging

1.0