The Value of Preoperative Volumetric Analysis by Computerised Tomography of Retrosternal Goiter to Predict the Need for an Extra- Cervical Approach

Abstract

Background: A thyroidectomy can be performed via acervical incision in most patients with retrosternal goiter.Aims: To investigate the correlation between the volumeof the mediastinal portion of the thyroid gland and theneed for an extra-cervical approach for retrosternalgoiter.Study Design: Diagnostic accuracy study.Methods: The measurement of craniocaudal lengthand the volume of the mediastinal component of thethyroid gland on computerised tomography images wasperformed in 47 patients with retrosternal goiter. Ofthese 47 patients, 8 (17%) required an extra-cervicalapproach and were classified as group 1, and 39 (83%)patients that required a cervical incision were classifiedas group 2. Receiver operating characteristic analysiswas performed to determine the cut-off value for thecraniocaudal length and the volume of the mediastinalthyroid mass, which significantly correlated with anextra-cervical approach for retrosternal goiter.Results: Reoperative surgery was significantly morefrequent in group 1 than in group 2 (50% vs 13%; p=0.03).The craniocaudal length of the mediastinal thyroid glandwas significantly longer in group 1 than in group 2(77±11 mm vs 31±21 mm, respectively; p=0.0001). Thevolume of the mediastinal component was significantlylarger in group 1 compared to group 2 (264±106 cm3vs 40±41 cm3, respectively; p=0.0001). The receiveroperating characteristic curve of craniocaudal lengthand the volume of the mediastinal component identified≥66 mm and ≥162 cm3 as the cut-off values with themaximum accuracy, respectively. The craniocaudallength of the thyroid mass below the thoracic inlet ≥66mm or a volume of the mediastinal portion ≥162 cm3 weresignificantly associated with an extra-cervical approach(p=0.0001). For predicting an extra-cervical approach,the sensitivity, positive predictive value and negativepredictive value of the cut-off value for craniocaudallength was 87.5%, 64% and 97%, respectively. Forpredicting an extra-cervical approach, the sensitivity,positive predictive value and negative predictive valueof the cut-off values for the mediastinal volume were100%, 89% and 100%, respectively.Conclusion: A thyroid volume of ≥162 cm3 extendingbelow the thoracic inlet was a significant determiningfactor for an extra-cervical approach, with a negativepredictive value for the extra-cervical approach of100% for retrosternal goiter with smaller volumes.Further studies with an increased number of patients areneeded to determine the value of volumetric analysisof retrosternal goiter to predict the need for an extracervicalapproach in retrosternal goiter.