evolution of parathyroid surgery using sestamibi imaging guidance
DESCRIPTION
Evolution of Parathyroid Surgery Using Sestamibi Imaging Guidance. David R. Byrd, MD Department of Surgery University of Washington. Disorders of Parathyroid Glands. - PowerPoint PPT PresentationTRANSCRIPT
Evolution of Parathyroid Surgery Using Sestamibi
Imaging Guidance
David R. Byrd, MD
Department of Surgery
University of Washington
Disorders of Parathyroid Glands• hypoparathyroidism -rare. Almost always caused
by excessive surgical removal of parathyroid tissue (iatrogenic) during thyroid or parathyroid surgery
• hyperparathyroidism (HPT): – primary - hi Ca++, hi PTH - usually due to single
adenoma (90%), cured by removal of adenoma
– secondary - lo Ca++, hi PTH, seen in chronic renal failure - not a surgical problem
– tertiary - hi Ca++, hi PTH, seen after renal transplant - hyperplasia of all 4 glands
Traditional Surgery for Hyperparathyroidism
• primary HPT - 4 gland exploration, remove adenoma, biopsy 3+ normal glands
• tertiary HPT (after renal transplantation) - 3 1/2 gland removal +/- forearm autotransplant
Complications of Parathyroid Surgery
• persistent HPT - 1-20% (experience dependent)• temporary or permanent hypocalcemia - 1-
20%• nerve injury - recurrent or superior laryngeal -
1-10%• bleeding - <5%
Unilateral Exploration for Primary HPT
• if: one abnormal, hypercellular gland and one normal gland found on one side, no contralateral exploration
• occasional use of preop thallium-technetium scan
• results of 5 studies - cure 93-100%
Indications for Operation in Asymptomatic Patient w/ Primary
HPT - NIH Consensus(1990)
• markedly elevated serum Ca++• episode of life-threatening hyperCa++• reduced creatinine clearance• renal stones• markedly elevated 24 hr urinary Ca++• substantially reduced bone mass (by DEXA
scan)• age <50 (relative indication for surgery)
Parathyroid Imaging
• Tc-99m sestamibi scan (Cardiolyte)• ultrasound• initially thought useful only in persistent or
recurrent disease• thallium-technetium subtraction scan - now
rarely used
Tc-99m Sestamibi Scan
• taken up by actively metabolizing tissues - salivary glands, thyroid, parathyroid glands
• over time, blood flow causes washout from thyroid and normal parathyroid glands
• delayed images show a discrete “hot spot” in 75-80% patients with primary HPT
• can be used to direct minimally invasive surgical approaches
Parathyroid Imaging - Tc-99m Sestamibi45 min Anterior 45 min LAO
2 HR 2 HR
submandibulargland
thyroid lobe
adenoma
Delayedviews
Right inferior pole parathyroid adenoma
15 min Ant 1 hr Ant 1 hr RAO
adenoma
15 min Ant 1 hr Ant
Right superior parathyroid adenoma
adenoma
Advances Enabling Localized Exploration
• Tc-99m sestamibi radioguided exploration
• rapid IOPTH assay - 1/2 life = 3-5 minutes
Rapid IOPTH Assay
• exploits short half life (3-5 minutes) of PTH• serum baseline level #1 prior to exploration• level #2 after exploration but before removal
adenoma• levels 5 & 10 minutes after adenoma removal• 5 minute level > 50% second baseline level =
high prediction of success-Irvin G, et al, 1993
Studies of IOPTH Measurement in HPT
solitary/ Uni/bilat. Cure rate # pts MGD exploration ( %)
Nussbaum 1988 12 12/0 8/4 100Chapuis 1996 173 -- 160/13 94Irvin 1993 61 -- -- 90Sofferman 1998 40 31/9 -- 100Carty 1997 67 58/9 42/25 99Irvin 1994 18 18/0 -- 89Starr 2001 50 38/12 0/50 92
Minimally Invasive Radioguided Parathyroidectomy (MIRP)
• only in patients who localize by pre-op sestamibi scan (75% with primary HPT)
• sestamibi scan performed 2-3 hours before exploration - timing crucial
• gamma probe used to find the “hottest” spot• ex vivo adenoma counts >20% background• no further dissection and no frozen section• if no adenoma found, 4 gland exploration
-Norman J, et al, 1997
MIRP - results
• 2 cm incision• local w/ sedation, out-patient procedure• 100% cure rate• no complications• mean operating time = 25 minutes• re-operative cure rate = 100%
-Norman J, 1997
Studies of MIRP in HPT
solitary/ Uni/bilat. Cure rate # pts MGD exploration ( %)
Martinez 3 2/1 -- --Gallowitsch 12 -- -- --Bonjer 62 49/10 -- 95Norman 15 15/0 14/1 --Norman 24 21/0 21/1 --Flynn 39 32/6 30/9 100
Evolution of Surgery for Primary HPT
• Preoperative sestamibi in all patients with primary HPT:– help decision whether to operate in selected patients
– localize adenoma to plan localized exploration
• Minimally invasive parathyroidectomy (MIP):– 2-4 cm incision
– often w/ local + sedation
– out-patient procedure
– +/- IOPTH testing - biochemical confirmation
• Endoscopic removal of parathyroid gland(s)
Right inferior parathyroid adenoma - 54F
15 min Ant 1 hr Ant 1 hr RAO
adenoma
IOPTH Testing and Results
Baseline #1 214
Baseline #2 157
5 minute post 32
10 minutes post 20
MIP findings - 500mg L inferior pole adenoma
F/U levels 3 mos: Ca++ = 9.5, PTH = 55 (both normal)
Case # 3
50M, asymptomatic:- serum Ca++ = 13.4- preop iPTH = 750- concern for carcinoma
Tc-99m sestamibi positive for intense uptake LIP
Immed Ant Delay Ant
IOPTH Testing and Results
Baseline #1 1259
Baseline #2 764
5 minute post 129
10 minutes post 93
Case #3: 50M, 4.2 LIP gm adenoma
Early F/U: Ca++ =8.8, PTH = 138 (low calcium, sl. elevated PTH)
Operation for Tertiary HPT
• standard operation remains 3 1/2 gland removal or total parathyroidectomy w/ auto transplant dorsal forearm
• Imaging not standard at present• selected patients may benefit from Tc-99m
sestamibi preop scan• role of IOPTH testing evolving