Imaging in Thyroid disorders Molecular imaging

Radionuclide imaging Isotope scanning

SPECT/CT

Dr Ahmed Esawy

Dr. Ahmed Eisawy

MBBS M.Sc MD

Dr Ahmed Esawy

Thyroid Scintigraphy: Indications and contraindications

. Thyroid uptake is useful for: 1. Differentiating hyperthyroidism from other forms of thyrotoxicosis (e.g., thyroiditis and thyrotoxicosis factitia). 2. Calculating iodine-131 administered activity for patients to be treated for hyperthyroidism or ablative therapy. . Whole-body imaging for thyroid carcinoma is useful for: 1. Determining the presence and location of residual functioning thyroid tissue after surgery for thyroid cancer or after ablative therapy with radioactive iodine. 2. Determining the presence and location of metastases from iodine-avid forms of thyroid cancer.

Dr Ahmed Esawy

Contraindications to Thyroid Scintigraphy : Administration of iodine-131 sodium iodide to pregnant or lactating patients (whether currently nursing or not) is contraindicated.

Dr Ahmed Esawy

Evaluation of the Thyroid Disease (Radioisotope Scanning)

Prior to FNA, was the initial diagnostic procedure of choice

Performed with: technetium 99m pertechnetate or radioactive iodine

Technetium 99m pertechnetate cost-effective

readily available

short half-life

trapped but not organified by the thyroid - cannot determine functionality of a nodule

Dr Ahmed Esawy

Imaging in Pediatric Thyroid disorders: Outline

Imaging modalities • ACR-SNM-SPR guidelines for thyroid scintigraphy Imaging in: 1. Congenital hypothyroidism 2. Thyrotoxicosis 3. Thyroid nodules 4. Radioiodine whole body scan in differentiated thyroid cancers .

Dr Ahmed Esawy

Normal scan of thyroid gland

Dr Ahmed Esawy

Dr Ahmed Esawy

GIOTRE

DIFFUSE FOCAL/NODULAR

MULTINODULAR UNINODULAR

NON-TOXIC TOXIC

Structural / Anatomy

Functional /biochemical

Dr Ahmed Esawy

Dr Ahmed Esawy

palpable cold nodule in a patient with Graves disease has a high likelihood of malignancy (4%)

mnemonic: CATCH LAMP

Colloid cyst

Adenoma (most common)

Thyroiditis

Carcinoma

Hematoma

Lymphoma, Lymph node

Abscess

Metastasis (kidney, breast)

Parathyroid

Probability of a cold nodule to represent thyroid cancer:

Dr Ahmed Esawy

Graves Disease

24/M

(+) thyrotoxic symptoms

131I thyroid scan & uptake Diffuse thyromegaly

Elevated RAI uptake values

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Graves’ disease

Dr Ahmed Esawy

Graves – Basedow disease

Dr Ahmed Esawy

Dr Ahmed Esawy

Congenital hypothyroidism: Scintigraphy

Dr Ahmed Esawy

Congenital hypothyroidism: Dyshormonogenesis

Dr Ahmed Esawy

10-day-old girl with sublingual thyroid gland..

Dr Ahmed Esawy

Ultrasound: Less sensitive in detecting ectopic thyroid (although has high specificity) NM thyroid scintigraphy : Tc 99m pertechnetate or I -123

Dr Ahmed Esawy

Preclinical stage: Scintigraphy may show increased uptake

• Difficult to distinguish Hashitoxicosis from

Graves disease by US or scintigraphy.

Dr Ahmed Esawy

14-day-old girl with thyroid agenesis.

Dr Ahmed Esawy

7-day-old boy with thyroid hemiagenesis.

Dr Ahmed Esawy

20-day-old girl with hemiagenesis and sublingual thyroid.

Dr Ahmed Esawy

9-day-old boy with thyroid gland in normal location. Dr Ahmed Esawy

Hashitoxicosis

Dr Ahmed Esawy

Graves disease / Hashimotos thyroiditis

Thyroid inferno Graves disease: 4 hour uptake of 40% Dr Ahmed Esawy

Subacute Thyroiditis

30/M

Hyperthyroid symptoms

131I thyroid scan

Thyroid not visualized

Only background radioactivity

Dr Ahmed Esawy

Iodine-131 radionuclide scan shows virtually no uptake of radioactive iodine by the thyroid gland.

Dr Ahmed Esawy

NODULAR GIOTRE

UNINODULAR

MULTINODULAR MNG

INACTIVE

COLD

TOXIC NODULE

TOXIC NODULE

TOXIC MULTINODULAR GIOTRE INACTIVE

COLD

MALIGNANT BENIGN Dr Ahmed Esawy

NODULAR GIOTRE

BENIGN ADENOMA NEOPLASM COLLIOD

Cyst Complex cyst

Focal thyrioditis

MALIGNANT

As function: biochemical - hot (toxic) - cold (N :TSH) cold nodule in a toxic thyroid (as may occur in Grave’s disease) Dr Ahmed Esawy

Cold Thyroid Nodule BENIGN TUMOR

Nonfunctioning adenoma Cyst (20%) Involutional nodule Parathyroid tumor

INFLAMMATORY MASS Focal thyroiditis Granuloma Abscess

MALIGNANT TUMOR Carcinoma Lymphoma Metastasis

Dr Ahmed Esawy

“Cold” nodule = focal defect

Dr Ahmed Esawy

Cold nodule, R lobe (99mTcO4)

Dr Ahmed Esawy

Dr Ahmed Esawy

Adenomatous nodule in a 66-year-old man with a low thyroid-stimulating hormone level of 0.1 mIU/mL. (a) Transverse US image shows a predominantly solid 2.4-cm nodule with well-circumscribed margins and a surrounding halo (benign US features). (b) Scintigraphic image obtained with 123I shows increased uptake in a hot nodule and relative photopenia of the adjacent normal thyroid tissue. The outline of the neck is not well visualized.

Dr Ahmed Esawy

Autonomous functioning thyroid adenoma

Dr Ahmed Esawy

Thyroid nodules. CT scan shows a mass in the posterior mediastinum (P), which displaces the air-filled esophagus to the right (arrow)

Thyroid nodules. Iodine-123 thyroid scan shows that a mass is a multinodular goiter (G). The posterior mediastinal mass is a hiatus hernia (H); the stomach (S) is shown. Further investigation revealed that thyrotoxicosis was the cause of the patient's symptoms

Dr Ahmed Esawy

Dr Ahmed Esawy

Autonomous adenoma

Initial scan - euthyreosis Repeat scan - hyperhyreosis Dr Ahmed Esawy

Cold nodule

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Thyroid SPECT Agents

99mTcO4

99mTc sestamibi

99mTc tetrofosmi

201TlCl

123I

131I

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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).

Dr Ahmed Esawy

131I SPECT/CT

Dr Ahmed Esawy

Thyroid cancer TCA with mets

Dr Ahmed Esawy

Dr Ahmed Esawy

99mTc sestamibi-Parathyroid

Dr Ahmed Esawy

Medullary Thyroid Carcinoma

Dr Ahmed Esawy

Dr Ahmed Esawy

Whole body 131I Scintigraphy

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

PET in TCA with increasing TG, negative TBS

Dr Ahmed Esawy

Dr Ahmed Esawy

Metastatic PTCA

Dr Ahmed Esawy

Metastatic PTCA

Dr Ahmed Esawy

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

Dr Ahmed Esawy

68Ga DOTA-TATE PET/CT SCAN

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Diffuse 18FDG uptake (benign)

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

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

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Interesting Case

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

Dr Ahmed Esawy

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.

Dr Ahmed Esawy

Interesting Case

Hypermetabolic osseous metastases in the cervico thoracic spine.

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Interesting Case

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

Dr Ahmed Esawy

Interesting Case

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

Dr Ahmed Esawy

TCA Staging

Dr Ahmed Esawy

TCA Follow-up & Monitoring

Dr Ahmed Esawy

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

Dr Ahmed Esawy

Thanks you so much!

Dr Ahmed Esawy