Parathyroid Scintigraphy SPECT/CT

Harvey A. Ziessman, MD

Nuclear Medicine

Department of Radiology

Johns Hopkins University

• Elevated s. calcium and parthormone

• Primary – Adenoma 85%

• Secondary – low calcium, renal

failure, 4 gland hyperplasia

• Tertiary – renal failure, autonomous

• Imaging is for localization

Hyperparathyroidism - Diagnosis

Sensitivity - NM, US, CT, MR

Author NM US CT MR Bonjer 81% 72% Staudenherz 78 58 Light 87 53 Tamaki 92 88 56 % Geati 95 81 83 Calxas 95 75 40 33% Wakamatsu 75 75 63 Average 88% 72% 60% 48%

Parathyroid Radiopharmaceuticals

• 1962 Cobalt-57 vitamin B-12

• 1964 Se-75 methionine

• 1977 Cesium-131

• 1979 Tl-201 chloride

• 1989 Tc-99m sestamibi (Cardiolite)

• 1996 Tc-99m tetrofosmin (Myoview)

• 1996 F-18 fluorodeoxyglucose (FDG)

• 1997 C-11 methionine

• Planar imaging - thyroid subtraction

• Dual-phase planar imaging

• SPECT – early or delayed

• SPECT/CT

• Combinations of these methods

Parathyroid MIBI – Methodology

Dual-isotope subtraction imaging

MIBI I-123 MIBI –Tc-99m

Sensitivity of Tc-99m sestamibi Subtraction (I-123 or Tc-99m)

Adenoma Hyperplasia Author Date #Pts. O’Doherty 1989 51 97% Wei 1994 23 92% 67% Hindie 1995 30 96% 67% Chen 1995 35 76% 50% Johnston 1996 46 78% Borley 1996 56 94% Hindie 1997 65 95% 80% Average 89% 66%

Tc-99m Sestamibi

• Differential washout of thyroid and

parathyroid – Doherty MJ, et al. JNM, ’92

Thyroid Parathyroid

MIBI

Tl-201 Tl-201

MIBI

Sestamibi – Dual phase

• Diagnostic utility of dual-phase method – Taillefer R, et al. JNM 1992

2 hrs 10 min

Tc-99m Sestamibi

• Differential washout – thyroid , para

– Parathyroid slower washout 60%

– Similar rate of washout

– Rapid washout

• Interpretation based on focal uptake

– Focal increase compared to thyroid

– Juxta-thyroidal/extra-thyroidal

Sensitivity of dual-phase MIBI Adenoma Hyperplasia Author Date # Pts. Taillefer 1992 23 90% Lee 1995 39 93% 60% Mazzezo 1996 73 82% McHenry 1996 124 81% Malhotra 1996 51 100% 56% Blocklet 1997 55 84% Blanco 1998 41 92% 63%

Average 88% 60%

Traditional Approach to Surgery

• Bilateral neck exploration

• Experienced surgeons

>90% success rate

• Value of scintigraphy

was questioned

• Small incision

• Fewer complications – hypoparathyroidism

– recurrent laryngeal nerve injury

• Shorter operating time/hospitalization

• This requires preoperative localization

Minimally invasive parathyroidectomy

Embryology of

parathyroid glands

Descend from 3rd and 4th

pharyngeal pouches

Superior glands

Phitayakorn, Am J Surg 2006

Inferior glands

77 %

22 %

41 %

Parathyroid usual gland location

57 %

• Cephalad

carotid bifurcation

• Posterior retro-esophageal

• Anterior to the thyroid

• Inferior pericardium

Parathyroid (ectopic) locations

Location of

ectopic glands

Superior glands Inferior

glands

Embryologic

descent

“ectopic”glands

Ectopic glands • Superior (40%)

– Tracheo-esophageal groove (43%)

– Retro- or para-esophageal (29%)

– Post. superior mediastinum (14%)

• Inferior (60%)

– Thymus/thyrothymic ligament (47%)

– Ant. superior mediastinum (22%)

Superior vs. inferior glands Why is this important?

• Superior glands

• Different arterial supply

• Behind the recurrent laryngeal nerve

• Thus, surgery has more risk

• Surgeons would like to know

SPECT

Advantages

• Improves contrast resolution

• Allows 3-dimensional localization

– R/L, sup./inf., ant./post.

SPECT – Tc-99m MIBI

• 338 patients - hyperparathyroidism

• Prospective study - 1994 to 2000,

• SPECT (triple-headed) at 2.5 hrs

Civelek, Udelsman, Surgery 2002; 131:149

SPECT – Tc-99m MIBI

• Correct lateralization (R, L) 87%

• Precise localization (sup., inf.) 82%

• Ectopic glands 93%

• Reoperative explorations 98%

Civelek, et al, Surgery 2002; 131:149

SPECT – Tc-99m MIBI

• 56 false positives (14%)

21 thyroid adenomas

6 thyroid cancer

29 unexplained

Civelek, Udelsman, Hopkins, Surgery 2002; 131:149

SPECT – Tc-99m MIBI

• Ectopic glands 19% (74) – 6 carotid sheath – 8 intra-thyroidal – 33 retro-esophageal space – 8 thymus – 5 mediastinum

– 14 superior glands – were inferior and posterior to lower poles

Civelek, Surgery 2002; 131:149

99mTc MIBI – SPECT vs. Planar

Sensitivity

Authors Pts. Planar SPECT

Billotey 1996 92 .86 .91

Chen 1997 66 .79 .78

Moka 2000 55 .56 .95

Schachter 2004 82 .78 .96

Lavely 2007 110 .79 .79

Nichols 2008 462 .84 .83

SPECT - Early vs. Delayed

Sensitivity Author # Patients Early Delayed

Perez Monte 37 .91 .74

Chen 49 .78

Schachter 82 .96

Civilek 338 .87

Nichols 462 .83

• Combines

– functional information of sestamibi

– anatomical information of CT

• Offers the potential to improve

• localization

• improve specificity

SPECT/CT?

• To determine:

– If hybrid SPECT/CT improves

localization over SPECT or planar

– If dual-time period SPECT/CT or

SPECT improves accuracy for

localization over a single-time period

Hopkins 2004-2006

Methods - Patient Population

• 210 consecutive patients

191 – primary hyperparathyroidism

192 – no prior parathyroid surgery

110 – had surgical resection by the time

of data analysis

103 – Single adenomas

SPECT/CT

• 2.5 mA low

dose x-ray tube

• CT acquisition

time: 10 min

• Rad dose:1 mSv

(100 mrem)

Methods - Imaging Protocol

• 30 mCi, Tc-99m Sestamibi

• Imaging at 10 min and 2 hrs

– Planar – ANT, RAO, LAO

– SPECT/CT of neck/thorax

Methods

• 6 image sets

Early Planar Late Planar

Early SPECT Late SPECT

Early SPECT/CT Late SPECT/CT

• 13 combinations of image sets

• 19 reads of each patient’s images

• 2 reading groups each with 2 readers

Single image Set Sens. PPV AUC

Planar - early 34% 75% 67%

Planar - delayed 45 73 72

SPECT - early 54 77 76

SPECT - delayed 54 73 76

SPECT/CT early 62 83 81

SPECT/CT delayed 54 70 76

Single-study RESULTS

<.03

NS

NS

Image Sets Sens. PPV AUC

Planar - early/delayed .57 .80 .78

SPECT- early/delayed .62 .82 .82

SPECT/CT - early/delayed .72 .87 .86

Paired studies - RESULTS

NS

<.05

Localization - Single Adenoma

Image Sets PPV AUC

* Early SPECT/CT-Late SPECT 91% 86%

* Early SPECT/CT-Late SPECT/CT 87% 86%

* Early SPECT/CT-Late Planar 86% 86%

Early SPECT-Late SPECT/CT 83% 82%

Early SPECT-Late SPECT 79% 81%

Early planar-Late planar 79% 78%

http://jnm.snmjournals.org/content/vol48/issue7/cover.shtml

10 min

2 hrs

ANT RAO LAO

Maximal

intensity

projections

MIPS

MIPS

Delayed

SPECT/CT

Early

SPECT/CT

Delayed

Early

MIPS

Delayed SPECT

POST ANT

3-D volume rendering - CTA and SPECT parathyroid scan

Nakada, et al. SNM 2010

Conclusion - SPECT/CT

• Combines functional information

from Tc-99m sestamibi SPECT

with CT anatomy

• Dual-phase SPECT-CT provides

the surgeon with accurate pre-op

three-dimensional localization

SAM Questions

• Which cell type MOST likely is

responsible for sestamibi uptake

A. Chief

B. Follicular

C. Oxyphil

D. Parafollicular

SAM Questions

• Which cell type MOST likely is

responsible for sestamibi uptake

A. Chief – secretes PTH

B. Follicular – thyroid hormone

C. Oxyphil – correct, mitochondria

D. Parafollicular – calcitonin

SAM Questions In primary hyperpara, which most

commonly causes false negatives

A. Lymphoma

B. Multigland disease

C. Single gland disease

D. Thyroid adenoma

SAM Questions In primary hyperpara, what most

commonly causes false negatives

A. Lymphoma

B. Multigland disease - correct

C. Single gland disease

D. Thyroid adenoma

Nuclear Medicine

PET

Johns Hopkins

Radiology