Gammagrafía de paratiroides y cirugía radiodirigida en el hiperparatiroidismo primario

Radio-guided procedure in minimally invasive surgery for primary hyperparathyroidism

Minimally invasive parathyroidectomy, of choice in most cases of primary hyperparathyroidism, shows a high detection rate, based on precise preoperative localization by MIBI scintigraphy (SPECT/CT) and neck ultrasound. Radioguided minimally invasive parathyroidectomy is an even more effective technique, which shortens surgical times, maintains minimal incision and few complications, allows immediate verification of parathyroid adenoma removal and is especially interesting in patients with ectopic lesions or cervical surgical history. In this paper, the indications, protocols and differences between the two available radioguided parathyroid surgery procedures (MIBI and R.O.L.L.) are exposed.

Intraoperative freehand SPECT as an alternative imaging technique for use in radioguided parathyroidectomy

Freehand single photon emission computed tomography (fhSPECT) is a technique that is used to monitor body's radioactivity intraoperatively. Accordingly, in this study, the feasibility of using fhSPECT for intraoperative 3D mapping in radioguided parathyroidectomy has been assessed. Patients, who were diagnosed with primary hyperparathyroidism consecutively, were scanned intraoperatively using fhSPECT to locate parathyroid adenomas before surgical procedure. The fhSPECT images were acquired intraoperatively using a declipse^®SPECT device (SurgicEye^TM). The fhSPECT protocol could not be completed due to the technical problems in one patient. Parathyroid adenoma was located in the first patient with no lateral deviation. Nevertheless, a deviation of 8 mm was detected in the depth of the parathyroid adenoma, which is the distance of parathyroid adenoma from the skin. A 20 mm lateral deviation and a 10 mm deviation in depth were detected in the second patient. In the third patient, as was the case in the first patient, parathyroid adenoma was located with no lateral deviation. However, there was a 15 mm deviation in the depth of the parathyroid adenoma. A 5 mm lateral deviation was detected in the fourth patient yet with no deviation in the depth of parathyroid adenoma. Finally, neither lateral nor vertical deviation was detected in fifth patient. Based on the findings of this study, it was concluded that the fhSPECT technology can be helpful to a certain degree in locating the parathyroid adenoma. However, further studies are needed to support the findings of this preliminary study.

Normocalcemic primary hyperparathyroidism: 99mTc SestaMibi SPECT/CT results compare with hypercalcemic hyperparathyroidism

CONTEXT

Normocalcemic primary hyperparathyroidism (nPHPT) is defined by an inappropriately increased serum PTH with normal serum calcium. Information about the diagnostic yield of parathyroid SPECT/CT scan and ultrasonography in nHPPT is limited and not conclusive.

PURPOSE

To evaluate the positivity rate of ^99m Tc-Sestamibi SPECT/CT scan in nPHTP compared with classical hypercalcemic PHPT (cPHPT).

MATERIALS AND METHODS

We retrospectively studied 125 patients with ^99m Tc-Sestamibi SPECT/CT scans. Subjects were divided into 2 groups: cPHPT (n = 93) and nPHPT (n = 32).

RESULTS

The detection rate of ^99m Tc-Sestamibi SPECT/CT in cPHPT was 86,02% (80/93) and 59.37%, in nPHPT (19/32), p = .003. No significant differences were seen between the SPECT/CT scan and ultrasonography (p = .28) and the agreement was higher in cPHPT than in nPHPT, p = .03. Sensitivity of ^99m Tc-Sestamibi-SPECT/CT was 98% on a per-patient basis (PPV 96%) and 91% on a per-lesion basis (PPV 88%). Glandular size was smaller in nPHPT (mean value 6.8 mm) and it was related only with PTH value.

CONCLUSION

Localization rate of parathyroid hyperfunctioning tissue with ^99m Tc-Sestamibi SPECT/CT is lower in nPHPT and it is related to a smaller glandular size. However, our study suggests that the positivity rate and sensitivity are nonnegligible by adding SPECT/CT. The reduction in the detection rate in nPHPT could benefit techniques with higher resolution such as ¹⁸ F-Choline PET/CT when the clinical context justifies it.

Radioguided surgery in primary hyperparathyroidism: a review of the different available techniques

Parathyroidectomy has evolved over the years from bilateral neck exploration to a single gland approach using minimally invasive surgery. The precise presurgical localization of the problem gland, using functional techniques, such as double-phase scintigraphy with [^99mTc] Tc-MIBI including SPECT-CT and PET-CT with [¹⁸F]-Choline and morphological ones, such as ultrasound have played a crucial role in this paradigm's shift. Radioguided surgery techniques have also adapted and grown with new contributions known for their indication in other fields. Thus, we currently have a wide range of techniques that have been added to the minimally invasive radioguided parathyroidectomy with [^99mTc] Tc-MIBI, which was the first on the stage and for which more experience exists. Among them, in this update, we will discuss parathyroidectomy using ultrasound-guided ROLL technique as well as with the use of ¹²⁵I seeds and finally, hybrid techniques that use radiotracer and fluorescence.

Update of the role of Nuclear Medicine techniques in the pre-surgical localization of primary hyperparathyroidism

Primary hyperparathyroidism is one of the most frequent endocrine disorders. Its diagnosis is biochemical. Imaging techniques are not useful for the diagnosis of this pathology; they are just tools for pre-surgical localization. In this continuing education, we will analyze the different imaging modalities used in this indication, focusing on Nuclear Medicine. The most commonly used imaging technique in this context is the parathyroid scintigraphy, nowadays double phase protocol with ^99mTc-MIBI and the double tracer with ^99mTc-MIBI/^99mTc-pertechnetate, associated in the first case to SPECT or SPECT/CT, in an early or late phase. The PET/CT with different tracers is showing good results, especially applied to cases of failure in the pre-surgical scintigraphic localization. We expose the results of the morphological imaging techniques as well as the usefulness of combining techniques.

Contribution of early SPECT/CT to 99mTc-MIBI double phase scintigraphy in primary hyperparathyroidism: Diagnostic value and correlation between uptake and biological parameters

AIM

To evaluate the value of ^99mTc-MIBI double-phase scintigraphy (DPS) and early SPECT/CT in the pre-surgical assessment of patients with primary hyperparathyroidism (PHPT). Also, to calculate the correlation between uptake and some biological parameters.

MATERIAL AND METHODS

Forty patients with PHPT were included: 37 solitary adenomas, 1 hyperplasia, and 2 double adenomas. Fifteen patients had ectopic glands. DPS and early SPECT/CT were acquired in all patients. Ultrasound was performed in 31/40. All patients underwent surgery, intra-operative iPTH measurements, and histopathological examinations. Qualitative DPS uptake was assessed and correlated to pre-surgical calcium, iPTH levels, gland weight, and maximum diameter.

RESULTS

In the planar study, there were 23 positive cases, 8 doubtful, and 9 negatives. With the SPECT/CT, 8/9 negatives cases were located. All doubtful cases were confirmed as positives. Gland location improved in 16 cases (12 ectopic). DPS+SPECT/CT failed to detect a solitary adenoma and at least one gland in three cases of multiglandular disease (MGD). The sensitivity by patient was: DPS 72.5%, DPS+SPECT/CT 90%, and ultrasound 42%. Ultrasound and scintigraphy (DPS+SPECT/CT) were concordant in 16/31 patients. For the rest of them, scintigraphy proved correct in 14/15, and both techniques failed in one case. There was a significant correlation between level of uptake and iPTH level, gland weight, and maximum diameter.

CONCLUSION

Early SPECT/CT improves sensitivity and the locating of parathyroid pathological glands and increases diagnostic confidence. iPTH level, glandular size, and weight are related to the qualitative assessment of ^99mTc-MIBI uptake in early DPS.

[Initial experience in intraoperative radiolocalization of the parathyroid adenoma with freehand SPECT and comparative assessment with portable gamma-camera]

Initial experience is presented by using freehand SPECT in the intraoperative radiolocalization of a parathyroid adenoma in 2 patients, one which was mediastinal. There is only one previous publication including 3 patients with parathyroid adenomas in usual parathyroid localizations. We also report for the first time a comparative assessment of results with portable gammacamera during the same surgery. In the operating room, we obtained images with portable gamma-camera and 3 D reconstruction with freehand SPECT from 15 min after iv injection of 5 mCi of (99m)Tc-MIBI. Both devices enabled the 2 adenomas to be detected intraoperatively, as well as checking activity of the excised gland and absence of significant uptake in surgical bed, with confirmation by intraoperative pre-postsurgical PTH levels, pathology and clinical follow-up for 10 months. Both devices accurately located the parathyroid adenomas intraoperatively, as well as confirmation of their extirpation, but freehand SPECT provided additional information of adenoma depth (mm) from the skin border, very useful for minimally invasive radio-guided surgery.

[Contribution of intraoperative scintigraphy to the detection of intrathyroidal parathyroid adenoma]

The intrathyroidal parathyroid adenomas (IPA) represent a rare cause of primary hyperparathyroidism whose location difficults appropriate surgical removal. We present the case of a patient diagnosed of parathyroid adenoma by presurgical scintigraphy in which finally during the parathyroidectomy, the lesion location was intrathyroidal. We consider that the intrasurgical parathyroid scintigraphy with (99m)Tc-MIBI by portable gammacamera is useful in the parathyroid adenomas removal and essential in the case of IPA.

[Ectopic parathyroid adenoma: Scintigraphic detection and radioguided surgery]

AIM

The aim of this study was to evaluate the role of (99m)Tc-MIBI parathyroid scintigraphy and radioguided parathyroidectomy on the diagnosis and treatment of primary hyperparathyroidism (PHP) due to ectopic adenomas.

METHODS

We reviewed 105 consecutive patients who underwent radioguided parathyroidectomy due to adenomas between March 2004 and December 2008. Of this group we studied 20 patients (19%) with ectopic adenomas. All patients had biochemical evidence of PHP, a positive parathyroid scintigraphy, radioguided detection with histolopathological confirmation of adenoma and at least 1 year-follow up. The parathyroid scintigraphy consisted on dual-phase planar and tomographic images (SPECT or SPECT/CT). During the parathyroidectomy, intraoperative PTH determinations (0, 7, 15 and 30 min after the parathyroidectomy) were done. The follow up consisted on blood examinations of PTH, calcium, phosphorus and vitamin D and assessment of renal function.

RESULTS

Parathyroid scintigraphy detected all adenomas. Scintigraphic and surgical findings were coincident in 18 cases (90%). The final adenoma localization was paraesophagic in 9 patients, cervicothymic in 5, posterior cervicomediastinal in 4, anterior mediastinal in 1 and parathymic in 1. The parathyroidectomy consisted on 12 minimally invasive surgeries, 2 unilateral cervicotomies, 4 bilateral cervicotomies and 2 sternotomies. No case of persistent or recurrent PHP was observed during the follow up.

CONCLUSIONS

Parathyroid scintigraphy (SPECT/CT) and radioguided surgery are effective methods on the localization and treatment of PHP due to ectopic adenomas. In our study the radioguided parathyroidectomy was successful in all cases and there was no evidence of persistent or recurrent hyperparathyroidism on the follow up.