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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%
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