Pre-operative localization of parathyroid adenoma

Dr Chan Man-yi

Tuen Mun Hospital

Primary hyperparathyroidism

Gold standard = bilateral neck exploration 95 – 98% at first exploration

Imaging used only after failed initial surgery

Etiology of primary hyperparathyroidism Solitary parathyroid adenoma 80-85%

Unilateral neck explorationMinimally invasive surgery

Foscused parathyroidectomyVideo-assisted parathyroidectomyVideoscopic parathyroidectomy

Minimally Invasive parathyroidectomy

Pre-operative Ultrasound Sestamibi scan CT MRI Angiography / selective

venous sampling

Intra-operative PTH assay Ultrasound Gamma probe

Ultrasound High frequency linear

transducer Carotid arteries – hyoid

bone – sternal notch Parathyroid adenoma

Gray-scale image Oval / bean-shaped Homogenously hypoechoic

Doppler Characteristic arc / rim of

vascularity Present in 83%

Lane MJ, Am J Roentgenol. Sept 1998; 171(3:819-23)

Sensitivity (55-83%)Ruda et al, Otolaryngol Head Neck Surg 2005;

132:359–372

USG by surgeon

Sensitivity of USG Specific side – 84% Specific quadrant – 79%

Sensitivity of USG + MIBI – 98%

Sestamibi scan

Istopic scan with technetium Tc 99m sestamibi

Single isotope dual phase scan IV injection early and delayed image Correlate with larger size / predominance

of oxyphil cells / presence of P-glycoproteinBhatnagar et al, J Nucl Med 1998;39:1617-1620

Carpentier et al, J Nucl Med 1998;39:1441-1444

Advantage Good at identifying ectopic glands in

mediastinum or deep cervical location Sensitivity (68-95%)

Ruda et al, Otolaryngol Head Neck Surg 2005; 132:359–372

Planar imagingSPECT/CT

SPECT

Planar, SPECT or SPECT/CT

Dual phase SPECT/CT > dual phase SPECT / planar

Early phase SPECT/CT + any form of delayed imaging > dual phase SPECT / planar

USG vs MIBI

Sensitivity of USG – 65% Sensitivity of MIBI-SPECT – 68% Detected only by one modality – 16% USG and MIBI complementary

USG + MIBI

USG + MIBI

Surgical failure w/o PTH – 2% With PTH – 1%

P=0.5

Reoperation?

163 patients with ?missed adenoma Pre-op localization surgery

140 unilateral exploration 18 mediastinal procedure

92% long term resolution of hypercalcemia

Sensitivity = 70%

Proposed strategy

? False positive

Assumed false +ve as surgeon failed to identified adenoma

All repeated scan showed same foci of radioactivity Errors in interpertation rather than in scan itself

John Doppman 1986

“The best localization study prior to primary exploration in a patient with primary hyperparathyroidism is to locate an experienced parathyroid surgeon”

Initial surgery: MIBI + USG if MIP Both +ve

Concordant result MIP (? IOPTH) Discordant result IOPTH mandatory if MIP

One +ve IOPTH mandatory if MIP Both -ve bilateral exploration

Re-operation MIBI as first line USG / CT / MRI FNA / arteriogram / SVS

An experienced surgeon is the key to success

END