title: Preoperative Diagnostic Strategy for Parotid Gland Tumors Using Diffusion-Weighted MRI and Technetium-99m Pertechnetate Scintigraphy: A Prospective Study.
abstract: OBJECTIVE
  Fine needle aspiration cytology (FNAC) for diagnosis of a parotid gland tumor is widely used but its sensitivity is low and non-diagnostic rate is relatively high. In contrast, core needle biopsy (CNB) has a higher sensitivity and lower rate of sampling errors but has a higher risk of injury to adjacent organs such as facial nerve than FNAC. Screening of patients with parotid gland tumors to identify cases of pleomorphic adenoma (PA) and Warthin tumor (WT) may allow CNB to be confined to patients without PA and WT. We established an algorithm for preoperative diagnosis and management of parotid gland tumor using diffusion-weighted MRI and 99mTc pertechnetate scintigraphy. This algorithm was developed with the goal of maximal reduction of the number of patients in whom CNB is required. The purpose of the study is to validate our algorithm prospectively.
  
  
  METHODS
  A prospective study was conducted in 71 cases who were newly diagnosed with parotid gland tumor and 53 cases were enrolled in the study. In the algorithm, PA (high apparent diffusion coefficient (ADC) mean≥1.5×10(-3) mm(2)/s) and non-PA (low ADCmean<1.5×10(-3) mm(2)/s) cases are first distinguished based on the ADCmean on diffusion-weighed MRI. Second, among suspected non-PA cases, WT and non-WT are distinguished using technetium-99m pertechnetate scintigraphy. CNB is then performed only in probable non-PA and non-WT cases.
  
  
  RESULTS
  Although CNB was only required in 40% (21/53) of all cases, we made a preoperative histopathological diagnosis with an accuracy of 87% (46/53) and we correctly diagnosed whether a tumor was benign or malignant with an accuracy of 96% (51/53). Preoperative surgical planning had to be changed during surgery in only one case (2%).
  
  
  CONCLUSIONS
  Our algorithm is valuable in terms of clinical practice with highly potential for preoperative diagnosis and with less risk of CNB procedure.
authors: Department of Otolaryngology-Head and Neck Surgery, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Masahiro
authors: M
authors: Kikuchi
authors: Department of Radiology, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Sho
authors: S
authors: Koyasu
authors: Department of Otolaryngology-Head and Neck Surgery, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Shogo
authors: S
authors: Shinohara
authors: Department of Clinical Pathology, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Yukihiro
authors: Y
authors: Imai
authors: Department of Radiology, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Megumu
authors: M
authors: Hino
authors: Department of Otolaryngology-Head and Neck Surgery, Kobe City Medical Center General Hospital, Kobe, Hyogo, Japan.
authors: Yasushi
authors: Y
authors: Naito
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010307:Parotid Neoplasms / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D011859:Radiography; D011877:Radionuclide Imaging / Q000379:methods; D012680:Sensitivity and Specificity; D013670:Sodium Pertechnetate Tc 99m / Q000008:administration & dosage*
chemical_list: D013670:Sodium Pertechnetate Tc 99m