Hyperparathyroidism Localization Techniques

2ns Paper Dynamic magnetic resonance angiography for localization 31

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Surgery vs. MRI 31

Surgery vs. MRI including dMRA 32

Enhancement patterns of adenomas in dMRA 32

Limitations of the study 32

3rd Paper the Rationale of MR Imaging 33

Pros of MRI 33

Cons of MRI 34

4th Paper 4D MRI for the Localization 35

Comparison of 4D MRI vs. 4D CT 35

5th Paper MR Appearance of parathyroid adenomas at 3 T 36

MRI table 37

Discussion and Conclusion 38

Bibliography and References41

Abstract

The project critically analysed the methodology involved in MRI localization technique of hyperparathyroidism. The results from five articles were mentioned and analysed. And the project discusses some of the significant advantages and the disadvantages of MRI as a localization technique of hyperparathyroidism. Also, there is a section that compares 4D MRI vs. 4D CT. There is a discussion that compares and contrasts Surgery and MRI and another segment that compares and contrasts Surgery vs. MRI including dMRA. On the last part, the projects outline some of the main recommendations that can be applied by the medical experts to ensure that they can locate the hyperparathyroidism at its early stage and the measures to be taken when using this technique to make sure that patients are kept safe and protected.

Aims of the project:

To review the literature regarding parathyroid imaging including evaluation of the quality of the evidence available

To examine the research regarding the possible role of MRI in parathyroid localization and set this in the context of the other imaging modalities

To discuss the types of MRI sequences that might be most effective for parathyroid localization

The introductory chapter

Introduction

It is well founded that the majority of patients (more than 81%) who experience hyperparathyroidism have less than two parathyroid glands affected; these patients have what is termed as a single adenoma. However, nearly 10% of individuals diagnosed with hyperparathyroidism have between three and two hyperactive glands, a situation that been best described by professionals as triple or double adenoma. The implication in this place is that about one-tenth of patients diagnosed with this medical condition have all of their four glands hyperactive, a scenario termed as four gland hyperplasia1. Given that hyperparathyroidism causes the increased activity of at least one of the four parathyroid glands, which ends up being hyperactive, it is common for professionals to recommend localization examinations immediately to patients whom have been diagnosed with hyperparathyroidism. Localization evaluations typically entail radical analyses that get implemented to help in pinpointing that gland(s) that are hyperactive2. Historically, localization evaluations were not rationally conducted before the first operative procedure because surgeons utilised a bilateral neck surgery to evaluate the four parathyroid glands and to identify the diseased gland3.

Even so, the need to conduct a focused parathyroidectomy, to evaluate and extract only the hyperactive parathyroid glands, catalysed technological innovations that allowed more precise pre-operative localization investigation. However, pre-operative localization examinations are inherently unnecessary in cases where bilateral neck evaluations are bound to take place. The most commonly conducted localization evaluations are an ultrasound and a Sestamibi on that neck, although an increase in the utilisation of other methods including that deploy high-resolution CT scans and MRI imaging have been reported bearing in mind their high accuracy potential4.

Imaging Modalities

Sestamibi Scans

As mentioned in the previous section, Sestamibi scans are considered the most attractive localization examination pattern when it comes to the identification of hyperactive glands in patients suffering from hyperparathyroidism. As mentioned by Griffith et al., Sestamibi scan localization strategy is inherently unique as it entails injecting a minimal amount of particular radioactive substances in a patients vein after which an X-ray image of the patient's chest, head, and neck is taken5. A close evaluation of preliminary findings that cause the accuracy of Sestamibi evaluations accords this method of hyperactive parathyroid glands an accuracy rate that ranges from 84% to 96%6. Even so, the precision and accuracy of the assessment is conventionally institution oriented and relies on the quality and capabilities of the apparatus and machines utilised in the localization examination, the methods deployed to carry out the analysis, and the competency of the professional is carrying out the hyperactive gland localization test. With this regard, Mourad et al maintain that centres that perform numerous parathyroid operations have higher chances of having accurate and precise Sestamibi scans7.

Among the outstanding advantages of utilising Sestamibi scans is that require equipment are highly accessible, making this method of hyperactive gland localization more available than others. Nonetheless, Sestamibi scans are highly recommendable and widespread in the clinical settings because of their peculiar ability to facilitate the localization of hyperactive glands within and outside the neck simultaneously8.

Ultrasound

The next method of performing hyperactive adenoma localization is through the implementation of ultrasound tests. Unlike Sestamibi scan localization strategies (which are two-step (the injection of radioactive materials and taking X-rays of patients suffering from hyperparathyroidism), this method deploys ultrasound in the identification of malfunctioning glands. It is worth mentioning that ultrasound localization strategies are associated with numerous benefits including the fact that they are inexpensive, non-invasive, and require minimal preparation9.

Regardless of its clear advantages, it is compelling to note that the effectiveness and accuracy of this method also rely upon the skills of the professional carrying out the examination. As such, it is highly important that the individual carrying out the ultrasound knows the key spots when looking for abnormal glands. A significant proportion of parathyroid professionals performs their ultrasound evaluation before carrying out the surgery for this reason9.

What is more, although ultrasound has reported being an effective strategy to identify abnormal glands in patients neck, this localization evaluation modality is often constrained from detecting defective glands that are located deep in the patient's neck, and the same applies in identifying hyperactive glands located in the chest. What is more, Shinzato and Ikehara observes that it is sometimes challenging to tell the difference between a thyroid nodule, a lymph node, and a parathyroid gland when ultrasound localization examination is deployed10. However, there is a 97% chance that what has been detected is the only diseased gland when Sestamibi scan and the ultrasound agree to the position of the defective gland11.

Ultrasound in PHPT

The two techniques used in the evaluation of patients that suffer from primary hyperparathyroidism are sonography and technetium Tc 99 sestamibi single-photon emission computed tomography (SPECT)12.

Sonography

Parathyroid and neck sonographic tests that were conducted during the research were supervised by a fellowship-trained radiologist (M.E.T.). Representative pictures obtained from thyroid and some abnormal parathyroid glands were taken by sonographers who used an LOGIQ 9 platform and a 12-MHz frequency linear array probe. Nodules in control positions for parathyroids were taken into consideration and some abnormally swollen parathyroid glands. Thyroid sonographic tests were also conducted13. The primary results of the sonographic examination and pertinent laboratory experiments and the clinical data recorded were then reviewed by the M.E.T. supervisors, who then went ahead to scan a few patients personally so that they could confirm any suspected abnormality in the results obtained14.

Technetium 99m Sestamibi SPECT

In this procedure, Technetium 99m sestamibi SPECT was carried out after the sonographic tests were though and all sonographic findings recorded in the data sheet15. The Patients, in this case, were imaged for ten minutes and three hours later, the injection of 25 mCi of Tc 99m followed. The SPECT imaging was done by the use a DST-XLI dual-head gamma camera and a collimator that had low-energy and high resolution. Each of the scanning session took a maximum period of thirty minutes each16. This duration of time ensured that the scanning was done to completion so as to avoid any possible errors. Single-photon outflow processed tomographic pictures with a 128 128 lattice were remade to make 3-dimensional projections, and spinning early and postponed pictures were seen after a while17. Centrally expanded or isolate tracer uptake in respect to the thyroid on either early or postponed pictures or both was viewed as demonstrative of an anomalous parathyroid organ18.

Results

Parathyroidectomy was conducted in 144 of the 172 patients available and assessed for all modalities. The sensitivity, specificity, and positive predictive value of sonography for hyperactive parathyroid adenoma were 74%, 96%, and 90%, separately. Sonography restricted a solitary adenoma or multi-glandular disease in 112 of 144 patients (78%). The sensitivity, specificity, and positive predictive value of SPECT were 58%, 96%, and 89%. Technetium 99m Sestamibi SPECT effectively anticipated an adenoma or multi-glandular disease in 88 of 144 patients (61%)19. Five patients with negative sonographic discoveries were appeared to have uni-glandular adenoma on Tc 99m Sestamibi SPECT. Accurate utilisation of Tc 99m Sestamibi SPECT (i.e., when sonographic findings were negative or doubtful) would have diminished the expense of imaging by 53%20. The following table shows the results of 8 different studies results on ultrasonography scan outcomes for parathyroid adenoma.

Study Patients(P) Intervention(I) Outcome

sensitivity Specificity

Abboud et al, 2008 doi: 10.1097/MLG.0b013e31817aecad.

253 patients

Retrospective study ultrasonography (US 98% Tublin ME et al., JUM February 1, 2009, vol. 28 no. 2 183-190

172 patients

ultrasonography (U...