Gamma probe-guided resection of a lymph node metastasis with I-123 in papillary thyroid carcinoma

Contribution of gamma probe-guided surgery to lateral approach completion thyroidectomy

OBJECTIVE

To evaluate the effectiveness of gamma probe performed with technetium Tc 99m-labeled pertechnetate in patients who underwent completion thyroidectomy after pathologic detection of incidental thyroid cancer following subtotal thyroidectomy.

METHODS

In this prospective study, we evaluated findings from patients with multinodular goiter who underwent gamma probe-guided lateral approach completion thyroidectomy after the pathologic detection of incidental thyroid cancer following subtotal thyroidectomy where partial thyroid tissue was left unilaterally or bilaterally. Patients who underwent the procedure between January 2003 and January 2007 were included. Thyroid scintigraphy; thyroid and neck ultrasonography examinations; and concentrations of thyroid hormones, thyrotropin (TSH), thyroglobulin, and thyroglobulin antibodies were evaluated before the second operation. Patients were administered 3 mCi technetium Tc 99m pertechnetate during anaesthetic induction, and we extracted suspicious thyroid tissue and tissue with activity above background activity levels according to gamma probe. Extracted tissues were evaluated pathologically.

RESULTS

Completion thyroidectomy was performed in 23 patients. Seventy-nine tissue samples were extracted; 49 were thyroid tissue and 30 were nonthyroid tissue. Mean thyroid tissue to background activity ratio (T:B) was 6.4 +/- 3.9 (range, 2-14.3), and mean thyroid bed (after excision) to background activity ratio (Tbed:B) was 1.2 +/- 0.2 (range, 0.8-1.7) (P = .001). Mean T:B and Tbed:B ratios of the nonthyroid tissue were 1.2 +/- 0.3 (range, 0.2-1.7) and 1.1 +/- 0.2 (range, 0.4-1.4), respectively (P = .001). The thyroid tissue T:B ratio was significantly higher than that of non-thyroid tissue (P<.001). Gamma probe labeling contributed to extraction of small amounts of thyroid tissue that could not be viewed by scintigraphy in 43% of patients.

CONCLUSIONS

Using gamma labeling, thyroid tissue shows significantly more activity than nonthyroid tissue. Gamma probe helps detect small, residual thyroid tissue that is buried in the scar tissue that cannot be distinguished by scintigraphy; therefore, it assists in the extraction of the maximum amount of thyroid tissue.

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.

Iodine-131 radio-guided surgery in differentiated thyroid cancer: Outcome on 31 patients and review of the literature

In the present study we investigated the role of radio-guided surgery with Iodine-131 (I-131) in a group of 31 patients with differentiated thyroid cancer (DTC) and loco-regional recurrent disease. The principal inclusion criterion for I-131 radio-guided surgery in our protocol was the presence of an I-131 positive loco-regional disease relapse after previous total thyroidectomy and at least 2 ineffective conventional I-131 treatments. The protocol we used consisted of the following steps. Day 0: all patients were hospitalized and received a therapeutic 3.7 GBq (100 mCi) dose of I-131 after thyroid hormone therapy withdrawal in condition of overt hypothyroidism (serum TSH levels>30 microUI/ml). Day 3: a whole body scan following the therapeutic I-131 dose (TxWBS) administration was acquired. Day 5: neck surgery was performed through a wide bilateral neck exploration using a 15-mm collimated gamma probe, measuring the absolute intra-operative counts and calculating the lesion to background (L/B) ratio. Day 7: post-surgery TxWBS was performed using the remaining radioactivity to evaluate the completeness of tumoral lesions extirpation. The final histologic examination showed the presence of 184 metastatic foci; among them, 98 (53.2%) were evident by both TxWBS and gamma probe evaluation, 76 (41.3%) were demonstrated only by gamma probe, and 10 (5.4%) were negative by both TxWBS and gamma probe evaluation. During follow-up (8 months to 4.9 years, mean 2.8 years), DxWBS, serum Tg levels off l-T4, and US showed absence of loco-regional disease in 25 patients (80.6%) while 6 patients had persistent disease. In conclusion, this protocol allowed us to identify neoplastic foci with high sensitivity and specificity, enabling us to remove loco-regional I-131 disease recurrences resistant to previous conventional I-131 therapies. Furthermore, the gamma probe allowed detection of some additional tumoral foci in sclerotic areas or located behind vascular structures that were not visualized at the pre-surgery TxWBS evaluation.

I-123-guided excision of metastatic papillary thyroid cancer

The use of a gamma probe for intraoperative localization of a cervical lymph node, which contained recurrent metastatic papillary thyroid cancer, facilitated a radio-guided minimally invasive outpatient surgical procedure and resulted in complete excision of clinically occult disease. The technique raises the issue of whether nonpalpable regional node recurrences should be locally excised, removed in a formal modified neck dissection, or treated with therapeutic doses of I-131.

Radio-guided surgery for persistent differentiated papillary thyroid cancer: case presentations and review of the literature

BACKGROUND AND AIMS

Persistent differentiated papillary thyroid cancer following radical locoregional surgery with metastases is an indication for limited reoperation or radioiodine therapy. Following injection of radioiodine, radio-guided surgery with application of an intraoperative gamma probe offers detection of metastases not seen by conventional imaging and control of completeness of resection.

PATIENTS/METHODS

We demonstrate four patients with locoregional metastases, two of them with additional distant metastases of papillary thyroid cancer following radical neck surgery. Postoperative radioiodine scans demonstrated persistent ipsilateral or contralateral cervical and mediastinal lymph node and isolated rib metastases.

RESULTS

Radio-guided surgery (RGS) leads to complete clearance of persistent lymph node metastases by limited recurrent neck surgery, resection of metastases not seen by conventional imaging and control of complete mediastinal lymph node dissection. Post-RGS scans allowed early diagnosis of occult diffuse or nodal pulmonary metastases in two patients. At last follow-up, 23 to 48 months following RGS and radioiodine therapy, there was no evidence of disease.

CONCLUSIONS

Radio-guided surgery is an additive surgical technique with low morbidity in selected patients with persistent thyroid cancer individualizing tumor therapy options in multimode oncological therapy.

Radioguided neck dissection in recurrent metastatic papillary thyroid carcinoma

Although radioguided surgery has been used for the excision of sentinel nodes in breast cancer and melanoma, sparse literature exists describing its use in thyroid cancer. We report a 69-year-old patient with a previous total thyroidectomy and lymph node dissection for papillary carcinoma who was subsequently found to have recurrent metastatic disease. After a therapeutic dose of radioactive iodine, a hand-held gamma-probe was used to selectively dissect the neck. The patient was offered radioguided revision neck dissection to remove the disease using residual radioactivity of the original therapeutic iodine 131 dose. Our case report seeks to demonstrate a recent example of our use of the gamma-probe in radioguided surgical excision of recurrent metastatic papillary thyroid carcinoma.

Radio-guided surgery of differentiated thyroid cancer using 131I or 99mTc-Sestamibi

The classical therapeutic approach to patients with differentiated thyroid cancer (DTC) is based on total or near-total thyroidectomy, followed by (131)I treatment and thyroid-stimulating hormone suppressive therapy. This approach allows complete cure in many patients, especially when the tumour is diagnosed at an early stage; it also allows long-term survival in patients with locoregional recurrences or distant metastases if they can be treated with (131)I. In contrast, when metastatic DTC deposits lose their ability to trap (131)I (non-functioning metastases), a worse prognosis is expected. Nevertheless, in patients with locoregional non-functioning recurrences, an early diagnosis and prompt surgical extirpation can lead to a favourable prognosis. In these cases, radical surgery is needed. This can be achieved with radio-guided surgery using a hand-held gamma probe and a tumour-seeking radiotracer to detect, intraoperatively, the smallest metastatic lesions. In this paper, we discuss the two principal techniques proposed in the literature for radio-guided surgery of non-functioning DTC metastatic recurrences, the first using high doses of (131)I and the second using low doses of 99mTc-Sestamibi.

Radio-guided surgery for lymph node recurrences of differentiated thyroid cancer

The objectives of this study were to assess the reliability of radio-iodine (131I) and a gamma probe for radio-guided surgery (RGS) to detect and then radically dissect lymph node recurrences (LNRs) in 10 patients with differentiated thyroid cancer (DTC). The major inclusion criterion was the presence of an iodine-positive LNR after previous total thyroidectomy and at least two ineffective 131I treatments. The protocol was designed as follows. Day 0: all patients were hospitalized and received 3.7 GBq of 131I in the hypothyroid condition. Day 3: presurgery whole-body scan with a therapeutic dose (TxWBS). Day 5: neck surgery using a gamma probe (Navigator GPS, AutoSuture, Italy), recording the absolute counts and the lesion/background (L/B) counts ratio. Day 7: post-surgery TxWBS performed using the remaining radioactivity. The presurgery TxWBS was positive in all patients, and the post-surgery TxWBS showed a negative pattern in 7 of 10 patients, suggesting the efficacy of the surgical procedure in most of the patients. After RGS the mean decrease in the absolute counts and the L/B counts ratio were 77.6% (52.7% minimum, 94.6% maximum) and 77.4% (52.3% minimum, 94.8% maximum), respectively. After operation the surgeon judged the procedure to be decisive in two patients, favorable in six, and irrelevant in two. The final histologic examination showed the presence of 78 lymph node metastases (mean of 8 per patient). There were 33 neoplastic lesions found by both TxWBS and gamma probe evaluations; 41 were shown only by gamma probe, and 4 were negative by both TxWBS and gamma probe evaluations. This protocol permitted us to look for neoplastic foci with high sensitivity and specificity, and we were able to remove lymph node metastases resistant to radioiodine therapy at a single session. The protocol also allowed detection of some additional tumoral foci in sclerotic areas or behind vascular structures that are difficult to identify and were not seen at the presurgery TxWBS evaluation. However, because of the possible false-negative results, complete excision must be undertaken in high risk patients with a local recurrence to eradicate the largest number of lymph nodes, independent of the counts measured by the gamma probe.

Gamma probe-guided lymph node dissection ('gamma picking') in differentiated thyroid carcinoma

The prognostic significance and the optimal management of regional lymph node metastases in patients with well-differentiated thyroid carcinoma continue to be controversial. The current surgical approach for nodal metastases is removal of grossly involved lymph nodes ("berry picking"). In patients with papillary thyroid cancer, this intraoperative sampling technique reveals tumor in only 15% to 60% of excised nodes. However, if a more extensive nodal dissection is undertaken, at least 70% of patients are found to have nodal disease. The authors have successfully used a gamma probe-guided lymph node dissection technique ("gamma picking") to identify visually undetectable micrometastatic lymph nodes at the time of surgical exploration. The authors used this technique in a 52-year-old man with papillary carcinoma of the thyroid that was diagnosed by fine-needle aspiration. Eighteen hours before the planned total thyroidectomy, the patient was given 1 mCi I-123 orally. Operative exploration revealed multiple tumor nodules in both lobes but no palpable lymph nodes in the neck. Total thyroidectomy was performed with complete extracapsular removal of both lobes and isthmus. The thyroid bed and the central and lateral nodal basins were scanned using a gamma probe (Neoprobe). Hot spots were identified, and these counts were compared with that of the background activity in the strap muscles. The gamma probe revealed four distinct foci of increased activity (10 times more than the background). These were resected and labeled separately for histopathologic study. Histologic analysis revealed bilateral, multifocal well-differentiated papillary carcinoma, with the largest tumor focus measuring 0.6 cm. Two of the four hot spots proved to be metastatic foci in small lymph nodes measuring less than 0.5 cm. The other two hot spots were thyroid remnants with no associated nodal tissue.

Sentinel lymph node biopsy in staging of differentiated thyroid cancer: a critical review

Sentinel lymph node biopsy has recently been utilized to map tumor lymphatics in patients with differentiated thyroid carcinoma. Currently, controversy centers around the feasibility and future role of this technique in the management of differentiated thyroid cancer patients. A review of the current literature in which sentinel lymph node biopsy was performed on patients with a diagnosis of differentiated thyroid cancer was undertaken. Sentinel lymph node biopsy has been carried out on thyroid cancer patients utilizing a vital dye technique, a radiotracer technique, and a combination of both techniques. In the current literature the average rate of sentinel node identification is 91% (range 66-100%) and when identified, the sentinel node accurately predicts the disease status of the neck in most patients (range 80-100%). Limitations to carrying out the sentinel node biopsy on thyroid cancer patients include staining of parathyroid glands, identification of lymph nodes draining into the mediastinum, and the 'shine through' effect. Sentinel lymph node biopsy is technically feasible, but for a disease in which nodal metastases are of debatable prognostic value, the clinical utility of sentinel lymph node biopsy in the management of patients with differentiated thyroid cancer appears less than promising.

Sentinel lymph node biopsy in patients with papillary thyroid carcinoma

BACKGROUND

It remains controversial whether modified radical neck dissection (MRND) for patients with papillary thyroid carcinoma improves prognosis. However, it is highly probable that the incidence of local recurrence is reduced by lymph node dissection. Sentinel lymph node (SLN) biopsy (SLNB) for patients with melanoma and breast carcinoma has been validated as an accurate method for assessing lymph node status. The objective of this study was to determine the feasibility of SLNB for the evaluation of cervical lymph node status in patients with papillary thyroid carcinoma.

METHODS

After injection of methylene blue around the tumor in 22 patients with papillary thyroid carcinoma, blue-stained lymph nodes were dissected as SLNs. After the SLNB, all patients also underwent subtotal thyroidectomy and MRND. SLNs and other lymph nodes were investigated with regard to their number, distribution, size, lymph node status, and ratio of metastatic area.

RESULTS

There was concordance between the SLN findings and the regional lymph node status in 19 of 21 patients (90.5%; 7 patients had both positive SLN and regional lymph node results, and 12 patients had both negative SLN and regional lymph node results). Two patients had negative SLN results but, in the end, had positive nonsentinel lymph nodes (NSLNs). The overall reliability rate of SLNB was 86.3% (19 of 22 patients). The authors experienced no complications with the use of methylene blue for the detection of SLNs.

CONCLUSIONS

SLNB using methylene blue is feasible technically and is safe, and the findings correlate with cervical lymph node status. Therefore, SLNB is a good technique for estimating the status of cervical lymph nodes in patients with papillary thyroid carcinoma.

Gamma probe-guided resection and scanning with TC-99m MIBI of a local recurrence of follicular thyroid carcinoma

A 30-year-old woman underwent two operations for multinodular goiter and follicular thyroid carcinoma. The residual thyroid tissue was ablated by I-131 therapy. After 7 years of follow-up, Tc-99m MIBI and I-131 scintigraphy were performed, because her serum thyroglobulin level was much higher compared with the control analysis performed in the sixth year. Tc-99m MIBI showed pathologic accumulation, which could be consistent with a local recurrence, whereas the results of I-131 scintigraphy were negative. The locally recurring follicular thyroid carcinoma was resected using a gamma probe and Tc-99m MIBI. The thyroglobulin level decreased to a normal level after surgery. This case shows that the intraoperative use of a gamma probe with Tc-99m MIBI allows localization of recurrent thyroid tissue in the scarred area in patients with increased radionuclide accumulation, and scanning of the affected area using the gamma probe may be helpful in determining whether resection is complete.

Surgical approach to thyroid nodules and cancer

Fine needle aspiration cytology is the mainstay of the diagnostic work-up of solitary thyroid nodules. Together with the patient's history and the clinical findings, cytology determines the indication for surgery. The minimal intervention for a suspicious nodule consists of thyroid lobectomy. If a diagnosis of malignancy is established, then we recommend total thyroidectomy for all follicular lesions that are larger than 1.5 cm and for high-risk papillary tumours. Near-total thyroidectomy may be appropriate for low-risk patients with papillary carcinoma in whom it is not intended to use radioactive iodine ablation. Whereas ipsilateral lymphadenectomy of the central (primary) compartment should routinely be performed, modified radical neck dissection is only indicated in evident nodal disease of the lateral (secondary) compartment(s). Patients with incidentally discovered differentiated thyroid carcinomas generally do not require complete thyroidectomy unless the tumours are larger than 1.5 cm in diameter or nodal involvement is present. A detailed description of the surgical technique for thyroidectomy and lymphadenectomy is given and an overview of surgical complications is provided.

Lymphoscintigraphy and gamma probe-guided surgery in papillary thyroid carcinoma: the sentinel lymph node concept in thyroid carcinoma

The authors report the use of lymphoscintigraphy and gamma probe-guided resection of the sentinel lymph node in a 65-year-old woman with clinically and cytologically indicated metastasizing papillary thyroid carcinoma. The results of the preoperative lymphoscintigraphy corresponded well with FDG PET and histologic findings, which gives promise of its validity in thyroid carcinoma. With experience in ultrasound-guided fine-needle aspiration biopsy, this method can be performed without any serious side effects for the patient. The validity of the sentinel lymph node concept in thyroid carcinoma and a possible improvement of nodal staging and local recurrence rate must still be proved.