Irregular cervical dissemination of tumours of the maxillo-facial region

SPECT-CT for topographic mapping of sentinel lymph nodes prior to gamma probe-guided biopsy in head and neck squamous cell carcinoma

INTRODUCTION

Lymphoscintigraphic planar imaging is a common procedure for sentinel lymph node imaging prior to lymph node biopsy, but fails to elucidate the specific lymphatic drainage. Composite functional/anatomical imaging (SPECT-CT) has the potential to enhance topographic orientation and diagnostic sensitivity of sentinel lymph node imaging, but has not yet been applied in the head and neck region.

STUDY DESIGN

A total of 30 patients were investigated. Planar imaging was 5 min, 265 x 265, right and left lateral; 500 kilocounts (Kcts) and SPECT (GE Millenium VG Hawk Eye 6 degrees/30s. step, 128 x 128, slice thickness 4.42 mm). Scans were performed 60 min after intra-mucodermal injection of 0.1 ml of 20 MBq 99mTc nanocolloid in patients with squamous cell cancer of the head and neck. SPECT studies were analysed by filtered back projection (FBP: Hann (0.7) prefiltering, Butterworth (0.5) postfiltering) and reconstruction (OSEM: Post Filter Hamming (0.85), 2 Iterations) and independently viewed with the co-registered CT image (eNTEGRA Functional Anatomical Fusion Vers 2.0216). The results were validated by comparing the results of each method employed in all 30 cases and intraoperative gamma probe-guided sentinel lymph node biopsy with histological examination in 13 of these patients.

RESULTS

The majority of patients had more than one sentinel node (mean 1.63, min. 0, max. 4). Seven out of the 30 studies demonstrated lymphatic flow to the contralateral side of the neck. Forty-nine sentinel nodes were identified by iteratively reconstructed SPECT-CT. Thirty-eight out of these 49 could be located in lymphoscintigraphic planar imaging, whereas only 24/49 were detected in filtered back projection, respectively. In 11 of the 30 cases, a clinically unpredictable pattern of lymphatic drainage was observed. No correlation was found between T stage or tumour location and the number of sentinel nodes detected. In one out of the 13 cases, in whom imaging was followed by intraoperative gamma probe-guided biopsy, no sentinel node could be detected with the probe in the proximity of the primary tumour, although the node was clearly discernible in the reconstructed SPECT-CT.

CONCLUSION

Composite functional/anatomical imaging (SPECT-CT) is feasible for sentinel lymph node detection. It enhances topographic orientation and diagnostic sensitivity with more sentinel nodes being detectable than by planar lymphoscintigraphy alone. Planar imaging should be accompanied by iterative reconstructed SPECT-CT to identify lymph nodes adjacent to the primary lesion. Such nodes are easily overlooked by planar lymphoscintigraphy and intraoperative gamma probes, as the high activity at the injection site can obscure their detection.

Clinical predictors for contralateral neck lymph node metastasis from unilateral squamous cell carcinoma in the oral cavity

The factors that predict contralateral (C-) lymph node metastasis (LNM) in patients with unilateral oral squamous cell carcinoma (SCC) were analyzed. One hundred and twenty-nine patients who had untreated SCC that originated from the lateral oral cavity, but not around the midline, were included. The impact of multiple clinicopathologic factors (sex, performance status, primary site, T-stage, number and level of ipsilateral LNM, growth type, histopathological grading, mode of invasion, extension across the midline, and systemic neoadjuvant/adjuvant chemotherapy) on time-to-C-LNM was assessed using the stepwise Cox proportional hazards model. The T-stage, number of ipsilateral LNM, and histopathological grading were independent and significant predictors for C-LNM. No C-LNM occurred in patients without ipsilateral LNM and in those with earlier cancers (T1 to T3) excepting tongue cancer. The results of this retrospective study suggested that patients with advanced tumors, multi-involvement of the ipsilateral neck nodes, or a higher degree of histopathological grading were at a higher risk for C-LNM.

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

Sentinel node scintigraphy in tumours of the head and neck region was combined with bone scintigraphy to provide anatomical landmarks in order to better locate the lymph node uptake. 99Tc(m)-nanocolloid (40 MBq) was injected in the peritumour region 1 h after the administration of bone-seeking 99Tc(m)-methylene diphosphonate (200 MBq). After 5 min, A-P and lateral projections of the head and neck region were acquired. In all the 26 patients examined, the surrounding anatomy was clearly depicted. In 23 patients, the lymphatic drainage was identified within 30 min. In these patients, all hot spots appearing outside the deposited activity could be located according to the neck region classification system of the Memorial Sloan-Kettering Hospital. No lymphatic drainage was visualized in the remaining three patients. The injection of bone-seeking activity 1 h before deposition of the radiocolloid provided images visualizing soft tissues as well as skeletal structures, thus improving the topical diagnosis. Correlation with the results of surgery was not performed. The administration of a small amount of bone-seeking activity prior to sentinel node scintigraphy of head and neck tumours improves the anatomical localization of the lymph node activity.