Localization of sentinel nodes in head and neck tumours by combined lymphoscintigraphy and bone scintigraphy

Multimodal image registration for localization of sentinel nodes in head and neck squamous cell carcinoma

PURPOSE

The aim of this clinical study was to propose a new method of preoperative 3-dimensional localization of the neck sentinel node in clinically and radiographically N0 squamous cell carcinoma of the oral cavity.

PATIENTS AND METHODS

This prospective study was carried out between August 2002 and August 2003. Ten patients with staged oral squamous cell cancer underwent this method of preoperative localization of the sentinel lymph node. At the present time, lymphoscintigraphy is recognized as the investigation of choice for the preoperative detection of sentinel nodes. Although we found it to be highly sensitive (100% in our study), it does not allow precise localization of the sentinel node in the anatomic context of the neck. To overcome this drawback, we used multimodal image registration applied to the cervical region in association with the imaging modalities of scintigraphy (single-photon emission computed tomography [SPECT] and gamma transmission) and computed tomography (CT). SPECT and gamma transmission (barium-133 sources) were carried out with a triple-head Philips-Marconi camera (Philips Medical System, Cleveland, OH), and CT was carried out with a General Electric console (GE Medical Systems, Milwaukee, WI). Gamma transmission was used to place the SPECT images in a reference cervical anatomic context (CT images). Registration involved the use of a manual method based on definition of homologous volume structures.

RESULTS

Preoperative image registration effectively localized the cervical sentinel node in 9 of the 10 patients, enabling a guided surgical approach in 90% of cases. The sentinel node was localized and resected using a hand-held gamma probe.

CONCLUSIONS

This original study adapts a new tool (multimodal image registration) to obtain precise preoperative localization of the cervical sentinel node in N0 oral squamous cell carcinoma. We confirmed the feasibility of this method in this indication. Although this method is a novel one, we believe that it will become extremely useful once a consensus has been reached on exclusive excision of the cervical sentinel node in oral cancers, as is the case for melanoma or breast cancer.

Sentinel node scintigraphy in breast cancer using a dual tracer technique

AIM

In order to depict the anatomy and improve the localization, sentinel node scintigraphy in breast cancer was combined with intravenous administration of pertechnetate. As this may reduce the detectability of weak 'hot spots', the number of lymph nodes detected at scintigraphy and at surgery in one group of patients was compared with that obtained in another group that had not received pertechnetate.

PATIENTS AND METHODS

The number of 'hot spots' at frontal and lateral views in 47 female patients at scintigraphy performed 2-3 h after subcutaneous injection of radiocolloid together with 25 MBq pertechnetate i.v. was compared in retrospect with that of 41 female patients who had not received pertechnetate. The number of lymph nodes detected at surgery using a hand-held gamma probe together with blue dye in the two groups was also compared. The washout kinetics of pertechnetate was studied in 10 patients.

RESULTS

There was no difference in the number of detected lymph nodes at any comparison. The kinetics study revealed a decreasing activity with time after correction for physical decay.

CONCLUSION

Administration of a 25 MBq pertechnetate i.v. in order to improve the anatomical localization at sentinel node scintigraphy in breast cancer does not reduce the detectability of radioactive lymph nodes.

Sentinel node detection in N0 cancer of the pharynx and larynx

Neck lymph node status is the most important factor for prognosis in head and neck squamous cell carcinoma. Sentinel node detection reliably predicts the lymph node status in melanoma and breast cancer patients. This study evaluates the predictive value of sentinel node detection in 50 patients suffering from pharyngeal and laryngeal carcinomas with a N0 neck as assessed by ultrasound imaging. Following 99m-Technetium nanocolloid injection in the perimeter of the tumour intraoperative sentinel node detection was performed during lymph node dissection. Postoperatively the histological results of the sentinel nodes were compared with the excised neck dissection specimen. Identification of sentinel nodes was successful in all 50 patients with a sensitivity of 89%. In eight cases the sentinel node showed nodal disease (pN1). In 41 patients the sentinel node was tumour negative reflecting the correct neck lymph node status (pN0). We observed one false-negative result. In this case the sentinel node was free of tumour, whereas a neighbouring lymph node contained a lymph node metastasis (pN1). Although we have shown, that skipping of nodal basins can occur, this technique still reliably identifies the sentinel nodes of patients with squamous cell carcinoma of the pharynx and larynx. Future studies must show, if sentinel node detection is suitable to limit the extent of lymph node dissection in clinically N0 necks of patients suffering from pharyngeal and laryngeal squamous cell carcinoma.