‘Low dose’ 99mTc-Sestamibi for radioguided surgery of primary hyperparathyroidism

Radioguided parathyroidectomy effective in pediatric patients

BACKGROUND

Radioguided parathyroidectomy (RGP) has been shown to be effective in adult patients with hyperparathyroidism (HPT), but the utility of RGP in pediatric patients has not been systematically examined. It is not known if adult criteria for radioactive counts can accurately detect hyperfunctioning parathyroid glands in pediatric patients. The purpose of our study was to determine the utility of RGP in children with primary HPT.

MATERIALS AND METHODS

A retrospective review of our prospectively maintained single-institution database for patients who underwent a RGP for primary HPT identified 1694 adult and 19 pediatric patients aged 19 y or younger. From the adult population, we selected a control group matched three to one for gland weight and gender and compared pre- and postoperative laboratory values, surgical findings, pathology, and radioguidance values between the control and the pediatric groups.

RESULTS

Excised glands from pediatric patients were smaller than those in the total adult population (437 ± 60 mg versus 718 ± 31 mg, P = 0.0004). When controlled for gland weight, ex vivo counts as a percentage of background were lower in the pediatric group (51% ± 5% versus 91% ± 11%, P = 0.04). However, ex vivo radionuclide counts >20% of the background were found in 100% of pediatric patients and 95% of the adult-matched control group.

CONCLUSIONS

All pediatric patients met the adult detection criteria for parathyroid tissue removal when a RGP was performed, and 100% cure was achieved. We conclude that RGP is a useful treatment option for pediatric patients with primary HPT.

Use of (99m)Tc 2-methoxyisobutyl isonitrile in minimally invasive radioguided surgery in patients with primary hyperparathyroidism: A narrative review of the current literature

The use of technetium-99m 2-methoxyisobutyl isonitrile (^99mTc MIBI) for assistance in minimally invasive radioguided surgery (MIRS) is growing in popularity as a safe, effective, and proficient technique used for parathyroidectomy in primary hyperparathyroidism (PHPT) treatment. Previously, the preferred treatment for PHPT was bilateral neck exploration (BNE), a very invasive, costly, and lengthy procedure. However, as a large majority (80–85% of cases of PHPT) are attributed to a single parathyroid adenoma (PA), a simpler more direct technique such as MIRS is a far better option. The following article is an exploration of the current literature concerning varied protocols utilizing ^99mTc MIBI for assistance in MIRS for patients undergoing treatment of PHPT. This technique boasts many advantageous outcomes for patients suffering from PHPT. These include a reduction in cost, operating time, and patient recovery; less evidence of post-surgical hypocalcaemia, less pain, and complications; superior cosmetic results; same-day discharge; and the possibility of local anaesthesia which is particularly beneficial in elderly patients. Better outcomes for patients with deep or ectopic PAs, reduced intra-operative complications, and improved cosmetic outcomes for patients who have previously undergone thyroid and/or parathyroid surgery are also advantageous. Of the literature reviewed it was also found that no patients suffered any major surgical complications such as laryngeal nerve palsy or permanent hypoparathyroidism using ^99mTc MIBI for assistance in MIRS.

Hyperparathyroidism in patients over 80: clinical characteristics and their ability to undergo outpatient parathyroidectomy

OBJECTIVE

Parathyroid surgery in elderly patients is commonly delayed due to perceived high operative risk. We evaluated the presentation of patients over 80 with primary hyperparathyroidism (PHPT) and their ability to tolerate outpatient, minimally invasive parathyroidectomy.

METHODS

We conducted a prospective cohort study of 150 consecutive patients over the age of 80 for the treatment of sporadic, nonfamilial PHPT. Presenting symptoms were compiled by questionnaire and compared between male and female (32 males, 118 females) and to 2600 patients under the age of 80. All patients underwent minimally invasive parathyroidectomy and were discharged from the recovery room. Operative findings and outcomes were assessed.

RESULTS

97% reported at least one symptom--the majority had five or more. The most common symptoms were fatigue, hypertension, and memory problems (occurring in 62%, 62%, and 57% of patients, respectively). Symptoms were similar between men and women, with the exception of bone pain being twice as common in women and kidney stones being twice as common in men (both p < 0.05). Preoperative calcium and parathyroid hormone (PTH) levels as well as the frequency of each symptom closely paralleled those of patients less than 80 years old with no significant differences. Average operative time was 18 +/- 5 minutes with discharge averaging 1.9 +/- 0.2 hours later. The incidence of single adenoma, double adenoma, or hyperplasia was identical to patients less than 80 (p = NS). Two patients required rehospitalization within 30 days of the procedure (congestive heart failure and pulmonary embolism), neither one for hypocalcemia. There were no deaths, and the cure rate was 99.3%.

CONCLUSION

PHPT is similar symptomatically, biochemically, and histopathologically between patients > 80 years old and younger patients. Modern techniques allow for small incisions, quick operative times, outpatient discharge, and uneventful recovery. Patients over 80 years old tolerate outpatient parathyroidectomy without event.

Role of 99mTc-sestamibi SPECT in accurate selection of primary hyperparathyroid patients for minimally invasive radio-guided surgery

PURPOSE

A prerequisite for optimum minimally invasive radio-guided surgery (MIRS) for primary hyperparathyroidism (PHPT) is the demonstration of significant uptake of (99m)Tc-sestamibi in a parathyroid adenoma (PA). The aim of this study was to evaluate the clinical role or (99m)Tc-sestamibi SPECT in selecting patients for this procedure.

METHODS

Fifty-four consecutive PHPT patients were evaluated by single-session (99m)Tc-pertechnetate/(99m)Tc-sestamibi planar subtraction scintigraphy, followed by (99m)Tc-sestamibi SPECT acquisition to localise hyperfunctioning PAs and assist in planning the surgical approach.

RESULTS

Scintigraphy showed the presence of a solitary PA in 47/54 patients (87%) and two or more PAs in four patients (7.4%); it was negative in the remaining three patients (5.6%). The overall sensitivity of (99m)Tc-sestamibi scintigraphy was 94.6%. In 7/54 patients, the PA was located deep in the para-oesophageal/paratracheal space. So far, 22 patients with scintigraphic evidence of a solitary PA (in four of whom the PA was located deep in the neck) have undergone successful MIRS using the low 37 MBq (1 mCi) (99m)Tc-sestamibi dose protocol. Intraoperative quick parathyroid hormone (QPTH) assay demonstrated a fall in all 22 patients, thus confirming successful removal of the hyperfunctioning PA. No major surgical complications were observed. After a period of follow-up ranging between 6 and 27 months (median 13 months), no case of persistent/recurrent PHPT was recorded. When comparing the parathyroid to background (P/B) ratio measured at planar and SPECT preoperative scintigraphy with that measured intraoperatively with the gamma probe, a good linear correlation was found between the SPECT and the intraoperative gamma probe measurements (r=0.89; p<0.01) but no correlation was found with planar scintigraphic data.

CONCLUSION

Our preliminary data suggest that measurement of the P/B ratio by means of (99m)Tc-sestamibi SPECT is more accurate in predicting the intraoperative measurements with the gamma probe. In this respect, a preoperative (99m)Tc-sestamibi SPECT acquisition should be recommended for better selection of PHPT patients in whom a MIRS approach can be offered.