1. Recent Advances IN THYROID IMAGING
Asia Oceania Thyroid Association Congress
Bali, Indonesia
October 22, 2012
Recent Advances IN THYROID IMAGING
Emerita a. Barrenechea MD, FPCP, FPSNM
Department of Nuclear Medicine
St. Luke’s Medical Center
Veterans Memorial Medical Center

2. Thyroid gland-very accessible

3. Mainstream Thyroid Imaging
Scintigraphy
Sonography
there have been several recent advances that are of interest to thyroidologists, radiologists and endocrinologists

4. 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

5. Ultrasonography Most common
Facilitate diagnosis of clinically apparent nodules
Most affordable
Primary imaging modality
American Thyroid Association
other authoritative bodies

6. 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

7. Normal echopattern

8. Suggestive of a follicular lesion

9. Hashimoto’s Thyroiditis

10. 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

11. 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

12. 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

13. Substernal Thyroid (CT)

14. 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

15. 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

16. MRI of thyroid gland

17. New Modalities 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

18. Radionuclide Imaging (Planar)
Standard views

19. Normal Variations

20. Graves’ disease

21. Thyroid Scan-UTS Correlation

22. “Cold” nodule = focal defect

23. Cold nodule, R lobe (99mTcO4)

24. Multinodular Goiter

25. Graves Disease 24/M (+) thyrotoxic symptoms 131I thyroid scan & uptake
Diffuse thyromegaly
Elevated RAI uptake values

26. 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

27. Autonomous functioning thyroid adenoma

28. Subacute Thyroiditis 30/M Hyperthyroid symptoms 131I thyroid scan
Thyroid not visualized
Only background radioactivity

29. Amiodarone Thyroiditis

30. Hashitoxicosis

31. Lingual thyroid

32. Whole Body 131I Scintigraphy

33. Remnant Thyroid
Complete Ablation
Complete ablation of
Residual thyroid
Tissue in neck
Very low/ Undetectable
Level of Tg

34. II III I IV Initial Presentation Post-SURGERY Post remnant Ablation
Functioning Mets In
Both Lungs II
III I
I-131 Therapy of
Functioning
Metastases
Proceed to
to stage IV IV

35. 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

37. Thyroid SPECT Agents 99mTcO4 99mTc sestamibi 99mTc tetrofosmi 201TlCl

38. 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.

39. 131I SPECT/CT

40. TCA with mets

42. 99mTc sestamibi-Parathyroid

43. Medullary Thyroid Carcinoma

45. Whole body 131I Scintigraphy
78/M, (+) 13-year FU, (+) rising Tg up to 1447 µg/L

46. PET in TCA with increasing TG, negative TBS

47. 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

48. 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

49. 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).

51. Metastatic PTCA

52. Metastatic PTCA

53. 131I WBS (–)
18FDG PET (–)
↑↑ Tg (56000 µg/L)

54. 68Ga DOTA-TATE PET/CT SCAN

55. 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

56. 18FDG Scan in Medullary TCA
PET only
CT Only
Intense FDG uptake in a hypodense nodule, L thyroid lobe
Serum Calcitonin: 800
Final Diagnosis: Medullary TCA
PET-CT Fusion

57. 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

58. Diffuse 18FDG uptake (benign)

59. 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

60. 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

61. Results 32 PTCA + 4 FTCA 14 PTCA Most frequent sites of metastases
↑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

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

63. 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

64. 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

65. 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

66. 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

67. 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.

68. 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.

69. 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

70. 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.

71. 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

72. 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.

73. 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

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

75. 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.

76. Interesting Case
Hypermetabolic osseous metastases in the cervico thoracic spine.

77. 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

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

79. Interesting Case
Hypermetabolic R hilar nodes. Differentials include inflammatory reaction vs. metastases.

80. TCA Staging

81. TCA Follow-up & Monitoring

82. 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

83. 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

84. Thanks you so much!