Correlation between preoperative predictions and surgical findings in the parotid surgery for tumors

Abstract

BackgroundTo compare preoperative CT/MRI based predictions with real surgical findings for deep lobe parotid gland surgery.MethodsThe study analyzed 122 parotidectomies (2004–2014) for benign tumor removal. The facial nerve, the Utrecht line, the Conn’s arc, and the retromandibular vein were used as landmarks for CT/MRI presurgical evaluation of patients. We assessed 106 CT images and 86 MRI images. The study compared preoperative evaluation of tumor location with its actual location that was revealed during the operation and assessed the importance of the landmarks.ResultsIn general, the agreement between preoperative CT prediction and actual location of the parotid tumors was achieved in 88.7 % (n = 94/106) when facial nerve line was used as a landmark. However, out of 14 tumors in the deep lobe only 5 were located correctly (35.7 %). Of the other existing CT landmarks, none showed more precision over others. The agreement between MRI based prediction and surgical results on actual location of the tumor was achieved in 94.2 %. Out of 12 MRI-investigated tumors in the deep lobe nine were located correctly that gives 75 % agreement with surgical results.ConclusionOur data suggests that no existing CT landmark can be accepted as completely reliable in cases when selective deep lobe parotidectomy is planned. If tumor location is suspected in the deep lobe of the gland, MRI imaging is necessary to confirm the diagnosis. An operating surgeon should be prepared that in some cases the true location of the tumor would be revealed only during surgery.

Management of Salivary Gland Malignancy: ASCO Guideline

“…MRI allows better delineation of the contours of a mass and offers significantly improved ability to characterize salivary gland masses and is preferred over other imaging modalities if there is concern for intracranial extension. 52,62,224,245,247,253,254 Diffusion-weighted imaging offers additional information that may increase the concern for malignancy. 101,246,251,277 The entire MRI scan should cover both the glands and neck for adenopathy, and IV gadolinium–based contrast agents should routinely be used.…”

Ultrasound can help to indirectly predict contact of parotid tumors to the facial nerve, correct intraglandular localization, and appropriate surgical technique

“…Other landmarks are the FN line, the Conn's arc, and the Utrecht line, which have accuracies ranging between 60% and 90% in various studies. 13,[18][19][20] To the best of our knowledge, this is the first prospective study to indirectly examine the diagnostic accuracy of the relationship between the FN and benign parotid lesions with US. In our study, the most important landmark was the RMV, which is considered a "hard" criterion (Figures 1 and 7).…”

“…However, most lesions are located in the posterior and inferior parts of the parotid gland. Other landmarks are the FN line, the Conn's arc, and the Utrecht line, which have accuracies ranging between 60% and 90% in various studies …”