Date of Award

3-2025

Degree Type

Dissertation

Degree Name

Master of Medicine (MMed)

First Advisor

Dr Khalid Makhdomi

Second Advisor

Dr Samuel Nguku Gitau

Department

Imaging and Diagnostic Radiology (East Africa)

Abstract

Background 

Parathyroid adenomas are the commonest cause of primary hyperparathyroidism. The primary mode of treatment is surgical excision which can only be achieved with pre surgical localization of adenomas. Ultrasound, CT and MRI can be used but the most sensitive and specific imaging modality is parathyroid scintigraphy with use of Sestamibi labelled with technetium 99 metastable radionuclide. A few studies have been done comparing dual phase, dual tracer and combined dual phase/tracer protocols with an apparent lack of consensus on which is superior.

Objectives

This study aimed to compare the positivity rates of the mentioned parathyroid scintigraphy protocols and identify the most effective one. It also sought to evaluate the association between parathyroid hormone and calcium levels with the detection of parathyroid adenomas.

Material and methods 

This was a retrospective study of 102 subjects with primary hyperparathyroidism imaged with parathyroid scintigraphy to evaluate parathyroid adenoma. The positivity rate of the dual tracer, dual phase and dual phase/tracer protocols were compared. Descriptive analysis of the data using frequencies and percentages was performed for categorical data while median and interquartile range were used for continuous data. Chi Square Test or Fisher’s Exact Test was used for group comparisons in univariate analysis.

Results

Dual tracer protocol had a higher positivity rate of 33.3% compared to 25.5% for the dual phase protocol. Combined dual phase/tracer protocol had the highest positivity rate (36.3%) of the three protocols. Combined dual phase/tracer protocol outperformed both the dual phase and dual tracer in sensitivity and negative predictive value. Our study found that elevated PTH and calcium levels were not consistently associated with higher positivity rates in parathyroid scintigraphy. While high PTH and calcium levels are often linked to parathyroid adenomas, their presence alone did not reliably predict scan positivity.

Conclusion

Combined dual phase/tracer protocol is superior to dual phase and dual tracer protocols alone in identifying parathyroid adenomas. While high PTH and calcium levels are typically expected in parathyroid adenomas, their presence alone did not reliably predict scan positivity in our study.

First Page

1

Last Page

33

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