Carotid body tumors: radioguided surgical approach

BACKGROUND: Carotid body tumours (CBTs) are very rare lesions which should be treated as soon as possible even when benign since small tumour size permits easier removal and lower incidence of perioperative complications and recurrence. Malignant forms are rare and they can be identified by lymph node invasion and metastases in distant locations. The need of reliable and effective diagnostic modalities for both primary CBTs and its metastases or recurrence is evident. The present study reviews our experience and attempt to define the role of colour coded ultrasound (CCU) and Somatostatin receptor scintigraphy (SRS) with Indium-111-DTPA-pentetretide (Octreoscan(®)) using both planar and single photon emission tomography (SPECT) technique in the diagnosis and follow-up of these uncommon lesions within a multidisciplinary approach. METHODS: From 1997 to 2008, 12 patients suffering from 16 CBTs (4 bilateral) were investigated by CCU and SRS-SPECT before and after surgery. All tumours were grouped according to Shamblin's classification in order to assess the technical difficulties and morbidity of surgical resection on the ground of their size and relationship with the carotid arteries. Intraoperative radiocaptation by Octreoscan(®)) was also carried out in all cases to evaluate the radicality of surgery. All perioperative scans were evaluated by the same nuclear medicine physician. RESULTS: Preoperatively CCU showed CBTs (four were not palpable) with a sensitivity of 100%. Radioisotope imaging identified the CBTs as chemodectomas in 15 cases while no radioisotopic uptake was detected in 1 vagus nerve neurinoma. No evidence of metastasis or multicentricity were seen by total body radioisotopic scans. Combined data from CCU and SRS-SPECT allowed to determine tumour size in order to select 7 larger tumours which were submitted to selective preoperative embolization. Intraoperatively Octreoscan demonstrated microscopic tumour leftovers promptly removed in 1 case and an unresectable remnant at the base of the skull in another case. During follow-up CCI and radioisotope scans showed no recurrence in 14 cases and a slightly enlargement of the intracranial residual as detected during surgery in 1 patient. CONCLUSION: CCU may allow an early and noninvasive detection of CBTs and hence safer operations. The combined use of CCU and SRS-SPECT provide useful data to identify those tumours and to evaluate their extent and carotid arteries infiltration. Radioisotope imaging is a sensitive modality to detect metastases and lymph node involvement that are markers of CBT malignancy. After surgery CCU and SRS-SPECT can be accurate modalities for surveillance for an early detection of CBTs recurrence.