RECENT ADVANCESIN THYROID IMAGING

Emerita a. Barrenechea MD, FPCP, FPSNMDepartment of Nuclear MedicineSt. Luke’s Medical CenterVeterans Memorial Medical Center

Asia Oceania Thyroid Association CongressBali, Indonesia

October 22, 2012

Thyroid gland-very accessible

Mainstream Thyroid Imaging

SonographyScintigraphy

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What is available?

• Planar/SPECT/SPECT-CT imaging (e.g. 99mTc-based radiotracers,123I, 131I)

• Positron emission tomography ( PET)

• Ultrasonography (USG), USG elastography

• Computed tomography (CT)

• Magnetic resonance imaging (MRI)

• Optical coherence tomography

Ultrasonography

Most common Facilitate diagnosis of clinically

apparent nodules Most affordable Primary imaging modality

American Thyroid Association other authoritative bodies

Ultrasonography

Patterns most frequently associated with thyroid CA Microcalcifications Relative hypoechogenicity of the nodule Irregular margins or absent halo sign Solid pattern and taller-than-wide

morphology Intranodular vascularization

Should not be used singly

Normal echopattern

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Suggestive of a follicular lesion

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Hashimoto’s Thyroiditis

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Thyroid Nodule Evaluation

Fine needle aspiration cytology is cornerstone Simple Useful Cost-effective BUT evaluation of non-diagnostic and

insufficient FNA samples continues to be a problem

Elastography

Sonographic estimation of rigidity/deformability of tissue change in Doppler signal after external

application of pressure/vibrations by tracking shear wave propagation

May correlate with: palpable consistency of goiter cytology of a nodule

May enhance cancer-prediction in non-cystic, non-calcified thyroid nodules or inflammatory conditions

Computed Tomography

3D image of internal organs Uses 2D X-ray images “Windowing” allows better visualization

of targeted organs Cannot detect small nodules Uses:

Detection of goiter or larger thyroid nodules

Evaluation of cervical lymphadenopathy Local tumor extension Mediastinal/Retrotracheal extension

Substernal Thyroid (CT)

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Magnetic Resonance Imaging

Anatomic imaging only Evaluation of thyroid size and shape Preferable than CT

No patient exposure to radiation No need for contrast study

Magnetic Resonance Imaging Arterial spin labeling (ASL)

Differentiation of autoimmune thyroid conditions

Treatment response evaluation in Graves disease

Diffusion weighted imaging (DWI) Apparent diffusion coefficient (ADC) can

be used to differentiate benign from malignant nodules (Schueller)

Benign = low signal intensities on DWI + high ADC

Malignant = high signal intensities on DWI + low ADC

MRI of thyroid gland

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Optical Coherence Tomography (OCT) high-resolution, real-time, cross-

sectional imaging of tissues Optical Coherence Microscopy (OCM)

high magnification cellular imaging 1–15 µ resolution High-resolution images comparable with

histopathologic images Both use infrared light

New Modalities

Radionuclide Imaging (Planar)

Standard views

Normal Variations

Graves’ disease

Thyroid Scan-UTS Correlation

“Cold” nodule = focal defect

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Cold nodule, R lobe (99mTcO4)

Multinodular Goiter

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Graves Disease

24/M (+) thyrotoxic

symptoms 131I thyroid scan &

uptake Diffuse thyromegaly Elevated RAI uptake

values

Diffuse Toxic Goiter

30/F Palpitations,

excessive sweating, irritability, anterior neck enlargement

99mTcO4 thyroid scan Diffuse thyromegaly Scintigraphic evidence

of increased gland uptake function 38 sec acquisition time Reduced background

tracer activity

Autonomous functioning thyroid adenoma

Subacute Thyroiditis

30/M Hyperthyroid

symptoms 131I thyroid scan

Thyroid not visualized

Only background radioactivity

Amiodarone Thyroiditis

Hashitoxicosis

Lingual thyroid

Whole Body 131I Scintigraphy

Remnant Thyroid Complete Ablation

Complete ablation of Residual thyroid Tissue in neck

Very low/ UndetectableLevel of Tg

Functioning MetsIn

Both Lungs

Initial Presentation Post-SURGERY Post remnant Ablation

I II III

Proceed toto stage IV

I-131 Therapy of Functioning Metastases

IV

SPECT/CT

Improved detection and localization of disease (superior to SPECT alone)

In radionuclide therapy, provides more insight into the effectiveness of targeting and may explain the observed response

Thyroid SPECT Agents

99mTcO4

99mTc sestamibi 99mTc tetrofosmi 201TlCl 123I 131I

131I SPECT/CT

131I SPECT-CT is more accurate than 18FDG PET-CT in well-differentiated thyroid cancer regional and distant metastasis residual/recurrent disease

The most important advantage of fusion 18FDG PET-CT and 131I SPECT-CT is detection of metastasis in normal sized lymph nodes.

131I SPECT/CT

TCA with mets

99mTc sestamibi-Parathyroid

Medullary Thyroid Carcinoma

Whole body 131I Scintigraphy

78/M, (+) 13-year FU, (+) rising Tg up to 1447 µg/L

PET in TCA with increasing TG, negative TBS

18FDG PET/CT

Well-established usefulness in WDTC if Tg (+) and WBS (–)

Helpful in anaplastic/medullary thyroid cancer

May be complimented by PET studies using 68Ga-DOTATOC and 18F-DOPA when looking for recurrent disease

Indications of PET/CT

residual or recurrent thyroid cancer WHEN elevated Tg + RAI scan (–) When localized, may require surgery or

radiotherapy Extent of poorly differentiated TCAs

& invasive Hurthle cell Cas Treatment response following

systemic or local therapy

BNMS Guidelines on TCA

Assessment of patients with elevated thyroglobulin levels and negative iodine scintigraphy with suspected recurrent disease.

To evaluate disease in treated medullary thyroid carcinoma associated with elevated calcitonin levels with equivocal or normal cross-sectional imaging, bone and octreotide scintigraphy - for alternative PET imaging with 68Ga- DOTA-octreotate (DOTATATE), DOTA-1-NaI3-octreotide (DOTANOC) or DOTA- octreotide (DOTATOC).

Metastatic PTCA

Metastatic PTCA

131I WBS (–)18FDG PET (–)↑↑ Tg (56000 µg/L)

68Ga DOTA-TATE PET/CT SCAN

68Ga DOTA-TATE PET/CT SCAN

Somatostatin receptor expression in thyroid CA

Patients with positive studies may be treated with Peptide Receptor Radionuclide Therapy (PRRT) 117Lu DOTA-TATE 90Y DOTA-TATE

18FDG Scan in Medullary TCA

Intense FDG uptake in a hypodense nodule, L thyroid lobe

Serum Calcitonin: 800

Final Diagnosis: Medullary TCA

PET only CT Only

PET-CT Fusion

Other findings in PET

↑FDG uptake in thyroid nodule as part of whole body study for cancer imaging = moderately high risk of malignancy Require further evaluation

Differentials = Graves' disease & thyroiditis

Otherwise, thyroid gland should be normal in PET

Diffuse 18FDG uptake (benign)

Philippine Data (2002 to 2012) 170 18FDG PET on 105 patients from

2005 to 2012 72 ♀ and 33 ♂ 17- to 83-years old Indications

116 – disease recurrence 6 – staging 11 – residuals 21 – response to therapy 13 – monitoring

Case Profile (Philippines) 77 – papillary thyroid cancer 9 – follicular thyroid cancer 11 – medullary thyroid cancer 2 – anaplastic thyroid cancer 2 – insular thyroid cancer 2 – squamous cell carcinoma 1 – adenosquamous thyroid

carcinoma 1 – Castle disease

Results

32 PTCA + 4 FTCA ↑Tg, (–) RAI scan, (+) 18FDG PET

14 PTCA Normal Tg, (–) RAI scan, (+) 18FDG PET

Most frequent sites of metastases Neck area Cervical lymph nodes Pretracheal nodes Lungs

Results

Most common resultant interventions: LN dissection Gamma knife therapy EBRT Chemotherapy ↑dose RAI therapy

Advantages of PET/CT

Can detect significantly more tumor sites

Only imaging modality that can screen for malignancy in multiple organs at once

Can lead to more appropriate clinical management

Other uses of 18FDG PET

Indeterminate thyroid nodules (3 cases)

Calcitonin-positive medullary TCA 18F-DOPA is superior to 18FDG for this One case was negative on 18FDG

Anaplastic thyroid cancer Insular thyroid carcinoma

Summary of 18FDG PET Impact on Thyroid Cancer Management Determination of definitive therapy

for RAI scan (–) WDTCA with elevated Tg

Evaluation of aggressive and difficult-to-treat TCA and poorly differentiated TCA

Discrimination of malignancy from thyroiditis in questionable thyroid nodules

Greatest impact of PET/CT

For WDTCA whose I-131 WBS is negative with increasing thyroglobulin but positive in PET as therapy is more definitive

For aggressive and difficult to treat TCA and undifferentiated TCA

For questionable thyroid nodules differentiating malignancy and thyroiditis

Interesting Case

CT (L) & fused PET/CT (R) in 56 y/o woman with lung cancer. Focal FDG uptake in R thyroid lobe with low CT attenuation (76 HU). PTCA on histopath.

Interesting Case

CT (L) & fused PET/CT (R) in 65 y/o man with esophageal cancer. Focal FDG uptake in L thyroid lobe with very low CT attenuation (3.6 HU). Diffusely increased FDG uptake in surrounding gland tissue. Follicular adenoma with lymphocytic thyroiditis on histopath.

Interesting Case

63/M with PTCA, s/p thyroidectomy, RAI therapy, thoracotomy, and radiotherapy

Neck MRI = L anterior neck nodule suspicious for recurrence

(+) pulmonary nodules on CT Biopsy of thyroid & lung nodules =

not malignant (+) RAI-avid right cervical lesion with

elevated Tg

Interesting Case

Calcified hypermetabolic R paratracheal node, multiple bilateral hypermetabolic non-calcified pulmonary nodules, multiple cervical, hilar and substernal nodes, and hypermetabolic lesions in a left rib and sternum, suspicious for metastases.

Interesting Case

65/F with PTCA, s/p thyroidectomy & multiple RAI therapies (cumulative dose = 1150 mCi)

elevated Tg at >800 (+) nodules in both lungs and left

adrenal (+) R lung base RAI-avid lesion on

post-therapy whole body scan

Interesting Case

Hypermetabolic right lung base mass corresponding to RAI-avid R lung base lesion seen on post-therapy scan, consistent with persistent metastatic thyroid cancer.

Interesting Case

67/F with PTCA, s/p thyroidectomy, L radical neck dissection, multiple RAI therapies & gamma knife treatment

elevated Tg, (–) RAI whole body scan (+) nodules in both lungs and left

adrenal (+) R lung base RAI-avid lesion on

post-therapy whole body scan CT showed possible recurrence in L

thyroid bed

Interesting Case

FDG-avid right cavernous sinus mass involving the petrous part of the temporal bone is most likely metastatic in nature.

Interesting Case

Hypermetabolic lesions/masses in the left neck extending to the thoracic inlet specifically to the left thyroid bed with hypermetabolic bilateral cervical lymphadenopathies are consistent with recurrent metastatic disease.

Interesting Case

Hypermetabolic osseous metastases in the cervico thoracic spine.

Interesting Case

77/M with insular TCA, s/p thyroidectomy

L thyroid nodule and lung nodules on pre-op CT

Post-op PET was requested for evaluation of disease extent

Interesting Case

Hypermetabolic lesion in the left thyroid bed may be inflammatory but residual disease cannot be ruled out.

Interesting Case

Hypermetabolic R hilar nodes. Differentials include inflammatory reaction vs. metastases.

TCA Staging

TCA Follow-up & Monitoring

Review of 2594 cases were reviewed for 1.5 years Focal and diffuse thyroid FDG uptake were

identified and were correlated with patholological diagnosis

3.8% (99/2594) showed incidental thyroid FDG uptake 46 diffuse (21 chronic thyroiditis) 53 focal

11/53 with focal FDG uptake FNAB results

4 benign 7 malignant (63.3%)

Use of SUV to delineate benign from malignant uptake is still undetermined

Chen, et al. Evaluation of thyroid FDG uptake incidentally identified on FDG imaging. NMC 2009 March 30(3):240-4

Conclusions Ultrasound and thyroid scans are still

the mainstay in imaging the thyroid gland

CT and MRI have limited values and can be utilized in identifying lymph nodes, local tumor extension, diff. thyroiditis and as FNA guide

PET/CT is best for WDTCA that have dedifferentiated hence negative on I-131-WBS but increasing thyroglobulin as well as in aggressive and difficult cases of TCA and certain suspicious nodules by FNAB

Thanks you so much!