Preoperative Diagnostic Strategy for Parotid Gland Tumors Using Diffusion-Weighted MRI and Technetium-99m Pertechnetate Scintigraphy: A Prospective Study

Abstract

ObjectiveFine 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.MethodsA 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 mm2/s) and non-PA (low ADCmean<1.5×10−3 mm2/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.ResultsAlthough 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%)ConclusionsOur algorithm is valuable in terms of clinical practice with highly potential for preoperative diagnosis and with less risk of CNB procedure.

Imaging quality of PROPELLER diffusion‐weighted MR imaging and its diagnostic performance in distinguishing pleomorphic adenomas from Warthin tumors of the parotid gland

“…Our study showed that the mean ADC is significantly higher in PMAs than in WTs, no matter whether on FSE‐PROP‐DWI or SS‐EP‐DWI. Our results are consistent with the majority of earlier studies on SS‐EP‐DWI but different to Fruehwald‐Pallamar et al's study, in which there was no difference between mean ADC in PMAs and WTs . Our results also showed that the FSE‐PROP‐DWI and the SS‐EP‐DWI both allow distinguishing PMAs from WTs significantly.…”

“…Metallic dental implants‐related magnetic susceptibility artifacts, motion artifacts and involuntary bulk motion‐related signal loss have been found to affect the imaging quality of SS‐EP‐DWI in parotid glands. Geometric distortion has also been demonstrated in SS‐EP‐DWI, not only in healthy parotid glands but also in parotid gland tumors …”

Multifocal Warthin’s Tumor: An Uncommon Presentation of Bilateral Cervical Lymphadenopathy

“…A low ADC indicates decreased diffusion of water molecules in tissue, suggesting more cellular tissue. Generally, malignant tumors tend to have lower ADC than benign tumors [ 18 ]. WT may be differentiated from malignant lesions based on “hot” uptake with 99m Tc pertechnetate scintography, which is due to the epithelial component's ability to concentrate 99m Tc pertechnetate but not secrete it [ 18 , 19 ].…”

“…Generally, malignant tumors tend to have lower ADC than benign tumors [ 18 ]. WT may be differentiated from malignant lesions based on “hot” uptake with 99m Tc pertechnetate scintography, which is due to the epithelial component's ability to concentrate 99m Tc pertechnetate but not secrete it [ 18 , 19 ]. WT also exhibits intense uptake on FDG-PET/CT [ 20 ].…”

Clinical Value of Fused PET/MRI for Surgical Planning in Patients With Oral/Oropharyngeal Carcinoma

“…Diagnostic MRI was performed using a 1.5 T scanner (Avanto, Siemens AG, Healthcare Sector, Erlangen, Germany). The MRI protocol used has been described elsewhere . Briefly, non–contrast‐enhanced T1‐weighted images, T2‐weighted images, and diffusion‐weighted images with b values of 0 and 1,000 sec/mm 2 were acquired in the axial plane.…”