Neck ultrasound & sestamibi scan, either or both for better detection and localization of hyperfunctioning parathyroid gland(s)

Neck ultrasound & sestamibi scan, either or both for better detection and localization of hyperfunctioning parathyroid gland(s)

Ashraf Hegab, MD; Mohammed A Nada,MD;  Waft Fouad Salib,MD;

Mohamed Seif, MD; Esam F Ebeid,MD; MRCS, (Eng); Abdel Wahab Ezzat,MD

Department of General Surgery, Ain Shams University, Cairo, Egypt.

Abstract

Aim of the work: To evaluate the usefulness of the combination of sestamibi scintigraphy

(SS) and neck ultrasonography (US) in patients with primary hyperparathyroidism (pHPT)

undergoing parathyroidectomy.

Patient and methods: Seventeen patients with proved pHPT were studied, excluding patients with persistent or recurrent disease. All patients underwent both SS and US prior to surgery, and   the   results  were    compared  with    operative  and   histological  findings.

Results: Fourteen patients had single adenoma, 2 patients had hyperplasia and a single

patient had multiple adenomas. US detected and localized accurately 10 cases, SS detected and localized the diseased parathyroid gland in 14 cases, while with combination we detected and localized the diseased parathyroid glands in 16 patients .

Conclusions:When the preoperative localization of the PT glands is chosen, the combination ofSS  and US represents a reliable noninvasive localization technique and should be considered for use in a complementary way beginning with US and  if US couldn't localize the diseased gland SS will be the next step.

Introduction:

Primary hyperparathyroidism (pHPT) is a common condition.  The incidence since the introduction of  multichannel analyzers is approximately 1:1000.1  In women  over  60 years of age the average annual incidence rate approaches 190  cases/100.000 per  year.2

Solitary parathyroid adenoma is the main cause

of pHPT in approximately  80% of cases and surgical resection of the pathological gland is curative. The  remaining cases  are usually secondary  to glandular hyperplasia and less commonly, multiple adenomas with parathyroid carcinoma which  is the  rarest cause.3

As parathyroidectomy improve pHPT the overall reported cure rates may reach 95- 98%

4, 5 so it is mandatory to detect the diseased

gland either pre or intra operative. In the 90Th of the last century many studies discussed the utility of  either neck  ultrasound (US)  or sestamibi scan (SS), however recently many studies supported  the efficacy  of combining

both US and sestamibi scan.2, 3, 6

As  most patients with primary hyperparathyroidism have a solitary adenoma, many can be treated with unilateral minimally invasive surgical techniques following accurate preoperative localization.3, 7

Ultrasound alone  permits localizing the adenoma site in relation to the thyroid gland, detects multiplicity specially if there isn't any nodularity of the thyroid gland and also detects small adenomas. On the other hand, sestamibi has its role in localization specially in ectopic parathyroid (15-20%) and  in  presence of nodular goiter.3

With the high prevalence of nodular goiter

in patients with primary HPT ranging in many series from 25% to 52% sestamibi scan became the most popular  preoperative technique  of localization.8

Aim of the work:

We aim from  this study  to evaluate the sensitivity  of ultrasound and sestamibi  each

separately and  in  combination aiming to establish a protocol which is reliable as regard the  efficacy and  the cost  effectiveness for detection and localization ofhyperfunctioning parathyroid gland(s) to establish the minimally invasive technique of parathyroidectomy as a routine procedure for  parathyroidectomy.

Patient and method:

Seventeen  patients  with  primary hyperparathyroidism were operated on over

36 months in Ain Shams University hospitals (March 2009-Februry 2011). The elevated parathyroid hormone was the main indicator of surgery rather than the ultrasound nor the

sestamibi scan, however none of our patients had renal impairment nor recurrent lesions, and all patients had been informed about the nature of the study and consented. All patients underwent both sestamibi scan and US prior to surgery and the results were compared with operative  and  histological  findings.

Results:

Intra-operative localization and postoperative histopathology showed that out of our 17 pHPT patients there were 14 patients with single adenoma, 2  patients  with hyperplasia and a single case with multiple adenomas).

Figure (1): Localization of a right inferior parathyroid adenoma by US & SS.

Figure (2): Minimally invasive surgical

exposure.

Figure (3):Surgicaldelivaryof the adenoma.

Figure (4): Postoperative wound after 1 week       Figure (5): Postoperative wound after 1 year.

Table (1):Results obtained using SS lliUl US (TP:true positive,FN: false negative).

Out of the 10 cases of p:FWT detected by US only  2 cases  couldn't be detected  by sestamibi scan.

Discussion:

The  best   localization technique for

parathyroid is a capable surgeon, 9,10 though if s one of the most famous statements  in surgery many clinical trials were conducted to evaluate and compare the different modalities of localizing hyperfunctioning parathyroid gland(s)t to come up with the best protocol that is not only accuratet but also relatively easy and cost effective.

The issue  of localizing the diseased parathyroid gland(s) still under debates as some authors reported higher sensitivity of localization ifcombining both Sestamibi scan and neck ultrasound (88.4% for sestamibi,

82.1% for US and 96.5% if combining both), however many authors found no benefit of this combination 3,6 and others found preoperative localization is of no benefit as in their expert hands bilateral neck exploration results in success rates exceeding 95% with minimal morbidity.ll,l2

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In our study which was performed on only

17 cases we found that the sensitivity of US alone to be only 59% which is low comparing to recent western studies (76-91%), 2 though it isn't far from others 64% 3 and we think this poor value could be operator dependent but this didn't lead us to ignore the role of US as there are 2 patients not detected by sestamibi and detected by US. However we believe that the sensitivity ofUS may improve using color and power Doppler sonography.

As reported in many studies the sestamibi sensitivity varies from 80% to 92% 8, 12 and in our study it was 82% , this is within the accepted  range reported  recently  in many studies.

We think  that  the 3 lesions  missed  on

scintigraphy did not show significant tracer uptake to allow detection and/or differentiation from physiologica11hyroid uptake as1he degree of sestamibi uptake inparathyroid adenomas has been reported to correlate with the size of gland and the cytological composition because it's  a non-specific tracer that is taken up by mitochondria, and therefore, any mitochondria­ rich cells may show uptake (greater uptake is

seen in adenomas with a predominance of oxyphil cells compared to  chief cells).

Barczynski et al, 2006  12 claimed their opinion of combination upon  the  high prevalence of thyroid disease among their cases and they  noticed that  the sensitivity of combining both  techniques was  90.7%  in

patients with goiter while when using US or sestamibi in patients with goiter the sensitivity were  (53.5%, 60.6%  respectively). While Lumachi & co-workers 2003 8 noticed that the sensitivity of combining both techniques is significantly higher than using each regardless the presence of goiter Table(2).

Table (2):Lumachi et al,results as regard the sensitivity of US and sestamibi scan in detecting parathyroid adenoma among patients. B

In  our  study we  noticed a significant improvement in sensitivity when we combined both techniques (94%) and amazingly it isn't far from Western studies results but we still think it might not be a true result as we had only 17 patients.

Grosso & co-workers 2007 6 reported that the combination ofSS and US does not enhance sensitivity nor specificity compared with either technique used alone and therefore is not cost­ effective; however, the  2 methods can  be complementary. Though we found there is a significant difference as regard  sensitivity between each of the techniques and if combined but we agree with the authors 6 in using both techniques in a  complementary manner and we suggest  that US should be used first and that  sestamibi scan  should  be reserved for negative US findings, because, unlike US, it can visualize adenomas inferior to the thyroid in sonographically ''silent'' regions, moreover, SS sensitivity did significantly correlate with the size of the PT adenoma, but not with the site of the abnormal PT glands.

Conclusion:

At  the  end, we  believe that the complementary noninvasive diagnostic protocol will support the  minimally invasive parathyroidectomy and then  it could be the classic technique of  parathyroidectomy.

References:

1- Conroy S, Moulias S, WassifWS: Primary hyperparathyroidism in the older person. Age and  Ageing  2003;  32(6):  571-578.

2- Lumachi F, Zucchetta P, Mazola MC, et al: Advantages of combined technetium-99m­ sestamibi scintigraphy and high resolution ultrasonography in parathyroid localization: Comparative study  in 91  patients with primary hyperparathyroidism. European J Endocrinology  2000; 143:  755-760.

3- Patel CN, Salahudeen  HM, Lansdown M, Scarsbrook AF: Clinical utility of ultrasound and 99TC sestamibi SPECT/CT for preoperative localization of parathyroid adenoma in patients with primary hyperparathyroidism. Clinical Radiology J2010; 65: 278-287.

4- Sosa  JA,  Powe  NR,  Levine  MA,  et al:

Threshold for  surgery and  surgical outcomes for  patients with  primary hyperparathyroidism: A national survey of endocrine surgeons. J Clinical Endocrinology and Metabolism 1998; 83:

2658-2665.

5- Delbridge LW, Younes NA, Guinea AI, et al:      Surgery   for   primary hyperparathyroidism    1962± 1996. Indications and outcomes. Medical  J of Australia 1998; 168: 153-156.