- Email: [email protected]
Limitations of Modern Imaging Techniques in Detection of Parotid Carcinoma
J Oral Maxillofac Surg 69:1826-1830, 2011
Limitations of Modern Imaging Techniques in Detection of Parotid Carcinoma Carolin Grimminger, MD,* Matthias Schmidt, MD,† Alexander Ahlbrecht, MD,‡ Michael Streppel, MD,§ and Simon F. Preuss, MD㛳 Most peripheral facial paralysis is of unknown cause and labeled as idiopathic or Bell’s palsy. Only for about 20% of peripheral facial paralysis cases can a specific cause be identified.1 The common diagnostic workup of peripheral facial nerve palsies includes routine investigations, such as a neurologic examination and a complete neuro-otologic screening (pure tone audiometry, caloric vestibular and stapedial reflex testing, Schirmer tear test, gustometry, serologic examination to rule out viral or bacterial infections, and brainstem audiometry in cases of equivocal findings),2 as well as electromyography of the facial muscles.3 Approximately 5% of facial nerve palsies can be demonstrated to have a neoplastic etiology, mainly parotid carcinoma. Facial nerve involvement is an important diagnostic marker for malignancy of a parotid tumor and might be the first symptom of parotid cancer.4 Most tumors of the parotid gland are palpable or found using ultrasonography, computed tomography, or contrast-enhanced magnetic resonance imaging (MRI). MRI is helpful because it provides better exposure of the deeper portion of the parotid gland and more precise discrimination *Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. †Department of Nuclear Medicine, University Hospital, Cologne, Germany. ‡Department of Radiology, University Hospital, Cologne, Germany. §Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. 㛳Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. Address correspondence and reprint requests to Dr Grimminger: Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Cologne, Kerpenerstrasse 62, Cologne 50924, Germany; e-mail: [email protected] © 2011 American Association of Oral and Maxillofacial Surgeons
0278-2391/11/6906-0087$36.00/0 doi:10.1016/j.joms.2010.07.067
between benign and malignant lesions owing to its high soft tissue differentiation.5,6 The present case report represents the rare, but possible, occurrence of a malignant parotid tumor that was not detected using the different imaging modalities. The present case underlines that a strong suspicion for a neoplastic cause of facial nerve palsy should be maintained if the patient has had incomplete recovery within 6 months, develops tics or spasms, the paralysis has a slow onset, or the patient develops paralysis of isolated branches of the facial nerve.7 The clinical and diagnostic electrophysiologic follow-up provides valuable information that could be of great importance in evaluating the cause of facial nerve palsy.
Case Report A 78-year-old, otherwise healthy, man presented to our institution with a history of progressive, left peripheral facial nerve palsy. The palsy had occurred 7 months before his presentation with an initial weakness of the zygomatic branch, resulting in difficulties in closing the upper eye lid. The patient had, therefore, initially consulted an ophthalmologist who recommended re-evaluation of the clinical status after a 3-month period without initiating any additional diagnostic studies. Owing to the slow progression of the facial palsy, a cranial, contrastenhanced MRI scan was initiated by an ear, nose, and throat specialist 3 months after the first symptoms had developed. The MRI scan did not reveal any signs of a neoplastic or inflammatory process along the route of the facial nerve, and no lesions were seen at the cerebellopontine angle. Four months later, the patient was admitted to our clinic with a complete facial nerve palsy of the left side. Except for the palsy, the physical examination did not show any other relevant signs or symptoms. In particular, no palpable mass was seen in the parotid gland nor were enlarged cervical lymph nodes found. Pure tone audiometry, caloric vestibular testing, ultrasonography of the parotid gland, and serologic testing did not reveal any relevant pathologic findings. We performed needle electromyography of the facial nerve that showed pathologic spontaneous activities and positive sharp waves of the left side, indicating electrophysiologic signs of neuronal degeneration. Because these signs were strongly suggestive of a neoplastic cause of the
1826
1827
GRIMMINGER ET AL
Despite these normal findings, the clinical course and electromyographic results were highly suspicious of a malignant disease affecting the peripheral facial nerve. Thus, surgical exploration of the peripheral course of the nerve was performed. The intraoperative situs showed a swollen facial nerve and diffusely macerated parotid gland tissue. Rapid section analyses established the diagnosis of a malignant epithelial tumor; thus, radical parotidectomy with facial nerve resection and ipsilateral neck dissection was performed. However, complete resection could not be achieved because of diffuse infiltration of the tumor toward the skull base. The final histologic analysis revealed a primary adenoid-cystic carcinoma (Stage pT4pN0cM0, R1, grade 2) of the left parotid gland, with perineural invasion of all facial nerve branches and lymphatic invasion. At 2 weeks postoperatively, functional facial nerve reconstruction with implantation of a gold weight in the upper eye lid and a sling plasty with allogenous fascia lata were performed. Subsequently, the patient underwent postoperative locoregional radiotherapy to a cumulative dose of 66 Gy. Follow-up examinations at 6 and 12 months after the surgical procedures showed no evidence of recurrent disease, and repeated follow-up MRI scans have confirmed the disease-free status.
Discussion
FIGURE 1. A, B, Coronal T1-weighted fat-suppressed gadopentetate-enhanced 5-mm MRI slices. White arrow on right indicates shim artifact, caused by heterogeneous magnetic field. Circle indicates region where tumor was later histologically proved, but showed no tumor delineation. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
palsy, another contrast-enhanced MRI scan of the head and neck region was performed. The left parotid gland was shown to be smaller and with a diffusely lower signal intensity, owing to shim artifact, a susceptibility artifact caused by a heterogeneous magnetic field (Figs 1 to 3). However, no other definable lesions were detectable in the head and neck region (Figs 1 to 3). Therefore, an 18-fluoro-2-deoxy-D-glucose positron emission tomography (F-18-FDG-PET) scan was performed that demonstrated physiologic distribution of glucose activity without any signs of a focal pathologic accumulation in the area of the head, skull base, or neck (Fig 4).
Although Bell’s palsy has been considered a diagnosis largely made by exclusion, several studies have shown that persistent peripheral facial paralysis for longer than 6 months is rarely idiopathic in origin.4,8 Furthermore, the absence of electrophysiologic regeneration or other regeneration of clinical function is suggestive of a neoplasm. In most cases, parotid tumors are palpable or detectable by ultrasonography or computed tomography, as the imaging methods of choice. However, it is well known that these applications can fail to detect small lesions, particularly if they are located in the deep, retromandibular portion of the parotid gland or close to the stylomastoid foramen.9,10 Contrastenhanced MRI provides greater accuracy in identifying soft tissue lesions. Regarding parotid gland lesions, MRI provides excellent anatomic information about the topographic relationships between the skull base, soft tissues, and the facial nerve with the potential to distinguish benign and malignant lesions.11 The significance of facial nerve enhancement in patients with Bell’s palsy remains somewhat controversial. Gebarski et al12 showed asymmetric enhancement owing to the topography of the circum neural arteriovenous plexus even in patients without any clinical facial nerve pathologic features. In Bell’s palsy, several recent published reports have described contrast enhancement along the course of the facial nerve in MRI scans correlating with the areas of greatest edema and inflammation, as well as the prognosis.7,11,13 In contrast, other investigators have found no correlation
1828
MODERN IMAGING LIMITATIONS AND PAROTID CARCINOMA
FIGURE 2. A, B, Sections of transversal native short T1-weighted inversion recovery 5-mm MRI sequences, including intratemporal region. White arrow highlights different signal intensity due to shim artifact on MRI scan. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
FIGURE 3. A, B, Transverse, gadopentetate-enhanced, T1-weighted MRI slices. Other than susceptibility artifact (white arrow), no tumorous lesion was detectable. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
1829
GRIMMINGER ET AL
FIGURE 4. F-18-FDG PET scan with 370 MBq showing physiologic distribution of activity without signs of focal pathologic accumulation in area of head, skull base, and neck. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
among the enhancement intensity, location, and recovery.14 The sensitivity, specificity, and accuracy in detecting malignant parotid lesions using contrast-enhanced MRI has been reported to be 87%, 94%, and 93%, respectively.5 However, acapsular tumors with atypical growth characteristics, such as diffuse infiltration of the surrounding tissues, such as was seen in the present case, might be undetectable using MRI. F-18-FDG-PET can be used to detect malignant tumors of various regions, and its usefulness in the differentiation of parotid gland lesions has been examined in several studies. Malignant parotid tumors showed significantly greater F-18-FDG uptake than either benign tumors or inflammatory lesions.15,16 Adams et al17 reported that PET has the greatest sensitivity and specificity for detecting lymph node metastases of head and neck
cancers compared with computed tomography, ultrasonography, and MRI. However, other investigators reported limitations of F-18-FDG-PET in the evaluation of parotid tumors because of a relatively high rate of false-positive results of about 30% owing to the high F-18-FDG uptake in benign tumors, such as cystadenolymphoma, pleomorphic adenoma, and oncocytoma.15,16 These specific considerations could explain the difficulties in the interpretation of F-18-FDG-PET results in parotid gland lesions. However, false-negative results are rare and have primarily been found in cases of small-size tumors.18 In conclusion, even if modern imaging techniques do not detect pathologic lesions, we suggest surgical facial nerve exploration in patients lacking signs of regeneration 6 to 8 months after the onset of the
1830 paralysis or with evidence of neuronal denervation by electromyography. Despite the progress of modern imaging techniques, this case report highlights that surgeons should be aware of the limitations of modern imaging techniques.
References 1. May M, Klein SR: Differential diagnosis of facial nerve palsy. Otolaryngol Clin North Am 24:613, 1991 2. Santos-Lasaosa S, Pascual-Millan LF, Tejero-Juste C, et al: [Peripheral facial paralysis: Etiology, diagnosis and treatment]. Rev Neurol 30:1048, 2000 3. May M, Hardin WB: Facial palsy: Interpretation of neurologic findings. Laryngoscope 88:1352, 1978 4. Jungehuelsing M, Sittel C, Fischbach R, et al: Limitations of magnetic resonance imaging in the evaluation of perineural tumor spread causing facial nerve paralysis. Arch Otolaryngol Head Neck Surg 126:506, 2000 5. Paris J, Facon F, Pascal T, et al: Preoperative diagnostic values of fine-needle cytology and MRI in parotid gland tumors. Eur Arch Otorhinolaryngol 262:27, 2005 6. Rumboldt Z, Gordon L, Bonsall R, et al: Imaging in head and neck cancer. Curr Treat Options Oncol 7:23, 2006 7. Freije JE, Harvey SA, Haberkamp TJ: False-negative magnetic resonance imaging in the evaluation of facial nerve paralysis. Laryngoscope 106:239, 1996 8. Jackson CG, Glasscock ME III, Hughes G, et al: Facial paralysis of neoplastic origin: Diagnosis and management. Laryngoscope 90:1581, 1980
MODERN IMAGING LIMITATIONS AND PAROTID CARCINOMA 9. Gosepath K, Hinni M, Mann W: The state of the art of ultrasonography in the head and neck. Ann Otolaryngol Chir Cervicofac 111:1, 1994 10. Weber AL: Imaging of the salivary glands. Curr Opin Radiol 4:117, 1992 11. Murphy TP, Teller DC: Magnetic resonance imaging of the facial nerve during Bell’s palsy. Otolaryngol Head Neck Surg 105:667, 1991 12. Gebarski SS, Telian SA, Niparko JK: Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation. Radiology 183:391, 1992 13. Yetiser S, Kazkayas M, Altinok D, et al: Magnetic resonance imaging of the intratemporal facial nerve in idiopathic peripheral facial palsy. Clin Imaging 27:77, 2003 14. Engstrom M, Thuomas KA, Naeser P, et al: Facial nerve enhancement in Bell’s palsy demonstrated by different gadolinium-enhanced magnetic resonance imaging techniques. Arch Otolaryngol Head Neck Surg 119:221, 1993 15. Uchida Y, Minoshima S, Kawata T, et al: Diagnostic value of FDG PET and salivary gland scintigraphy for parotid tumors. Clin Nucl Med 30:170, 2005 16. Schmidt M, Schmalenbach M, Jungehulsing M, et al: 18F-FDG PET for detecting recurrent head and neck cancer, local lymph node involvement and distant metastases: Comparison of qualitative visual and semiquantitative analysis. Nuklearmedizin 43:91, quiz 2, 2004 17. Adams S, Baum RP, Stuckensen T, et al: Prospective Comparison of 18F-FDG PET with Conventional Imaging Modalities (CT, MRI, US) in lymph node staging of head and neck cancer. Eur J Nucl Med 25:1255, 1998 18. McGuirt WF, Keyes JW Jr, Greven KM, et al: Preoperative identification of benign versus malignant parotid masses: A comparative study including positron emission tomography. Laryngoscope 105:579, 1995
Limitations of Modern Imaging Techniques in Detection of Parotid Carcinoma Carolin Grimminger, MD,* Matthias Schmidt, MD,† Alexander Ahlbrecht, MD,‡ Michael Streppel, MD,§ and Simon F. Preuss, MD㛳 Most peripheral facial paralysis is of unknown cause and labeled as idiopathic or Bell’s palsy. Only for about 20% of peripheral facial paralysis cases can a specific cause be identified.1 The common diagnostic workup of peripheral facial nerve palsies includes routine investigations, such as a neurologic examination and a complete neuro-otologic screening (pure tone audiometry, caloric vestibular and stapedial reflex testing, Schirmer tear test, gustometry, serologic examination to rule out viral or bacterial infections, and brainstem audiometry in cases of equivocal findings),2 as well as electromyography of the facial muscles.3 Approximately 5% of facial nerve palsies can be demonstrated to have a neoplastic etiology, mainly parotid carcinoma. Facial nerve involvement is an important diagnostic marker for malignancy of a parotid tumor and might be the first symptom of parotid cancer.4 Most tumors of the parotid gland are palpable or found using ultrasonography, computed tomography, or contrast-enhanced magnetic resonance imaging (MRI). MRI is helpful because it provides better exposure of the deeper portion of the parotid gland and more precise discrimination *Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. †Department of Nuclear Medicine, University Hospital, Cologne, Germany. ‡Department of Radiology, University Hospital, Cologne, Germany. §Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. 㛳Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital, Cologne, Germany. Address correspondence and reprint requests to Dr Grimminger: Department of Otorhinolaryngology, Head and Neck Surgery, University Hospital Cologne, Kerpenerstrasse 62, Cologne 50924, Germany; e-mail: [email protected] © 2011 American Association of Oral and Maxillofacial Surgeons
0278-2391/11/6906-0087$36.00/0 doi:10.1016/j.joms.2010.07.067
between benign and malignant lesions owing to its high soft tissue differentiation.5,6 The present case report represents the rare, but possible, occurrence of a malignant parotid tumor that was not detected using the different imaging modalities. The present case underlines that a strong suspicion for a neoplastic cause of facial nerve palsy should be maintained if the patient has had incomplete recovery within 6 months, develops tics or spasms, the paralysis has a slow onset, or the patient develops paralysis of isolated branches of the facial nerve.7 The clinical and diagnostic electrophysiologic follow-up provides valuable information that could be of great importance in evaluating the cause of facial nerve palsy.
Case Report A 78-year-old, otherwise healthy, man presented to our institution with a history of progressive, left peripheral facial nerve palsy. The palsy had occurred 7 months before his presentation with an initial weakness of the zygomatic branch, resulting in difficulties in closing the upper eye lid. The patient had, therefore, initially consulted an ophthalmologist who recommended re-evaluation of the clinical status after a 3-month period without initiating any additional diagnostic studies. Owing to the slow progression of the facial palsy, a cranial, contrastenhanced MRI scan was initiated by an ear, nose, and throat specialist 3 months after the first symptoms had developed. The MRI scan did not reveal any signs of a neoplastic or inflammatory process along the route of the facial nerve, and no lesions were seen at the cerebellopontine angle. Four months later, the patient was admitted to our clinic with a complete facial nerve palsy of the left side. Except for the palsy, the physical examination did not show any other relevant signs or symptoms. In particular, no palpable mass was seen in the parotid gland nor were enlarged cervical lymph nodes found. Pure tone audiometry, caloric vestibular testing, ultrasonography of the parotid gland, and serologic testing did not reveal any relevant pathologic findings. We performed needle electromyography of the facial nerve that showed pathologic spontaneous activities and positive sharp waves of the left side, indicating electrophysiologic signs of neuronal degeneration. Because these signs were strongly suggestive of a neoplastic cause of the
1826
1827
GRIMMINGER ET AL
Despite these normal findings, the clinical course and electromyographic results were highly suspicious of a malignant disease affecting the peripheral facial nerve. Thus, surgical exploration of the peripheral course of the nerve was performed. The intraoperative situs showed a swollen facial nerve and diffusely macerated parotid gland tissue. Rapid section analyses established the diagnosis of a malignant epithelial tumor; thus, radical parotidectomy with facial nerve resection and ipsilateral neck dissection was performed. However, complete resection could not be achieved because of diffuse infiltration of the tumor toward the skull base. The final histologic analysis revealed a primary adenoid-cystic carcinoma (Stage pT4pN0cM0, R1, grade 2) of the left parotid gland, with perineural invasion of all facial nerve branches and lymphatic invasion. At 2 weeks postoperatively, functional facial nerve reconstruction with implantation of a gold weight in the upper eye lid and a sling plasty with allogenous fascia lata were performed. Subsequently, the patient underwent postoperative locoregional radiotherapy to a cumulative dose of 66 Gy. Follow-up examinations at 6 and 12 months after the surgical procedures showed no evidence of recurrent disease, and repeated follow-up MRI scans have confirmed the disease-free status.
Discussion
FIGURE 1. A, B, Coronal T1-weighted fat-suppressed gadopentetate-enhanced 5-mm MRI slices. White arrow on right indicates shim artifact, caused by heterogeneous magnetic field. Circle indicates region where tumor was later histologically proved, but showed no tumor delineation. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
palsy, another contrast-enhanced MRI scan of the head and neck region was performed. The left parotid gland was shown to be smaller and with a diffusely lower signal intensity, owing to shim artifact, a susceptibility artifact caused by a heterogeneous magnetic field (Figs 1 to 3). However, no other definable lesions were detectable in the head and neck region (Figs 1 to 3). Therefore, an 18-fluoro-2-deoxy-D-glucose positron emission tomography (F-18-FDG-PET) scan was performed that demonstrated physiologic distribution of glucose activity without any signs of a focal pathologic accumulation in the area of the head, skull base, or neck (Fig 4).
Although Bell’s palsy has been considered a diagnosis largely made by exclusion, several studies have shown that persistent peripheral facial paralysis for longer than 6 months is rarely idiopathic in origin.4,8 Furthermore, the absence of electrophysiologic regeneration or other regeneration of clinical function is suggestive of a neoplasm. In most cases, parotid tumors are palpable or detectable by ultrasonography or computed tomography, as the imaging methods of choice. However, it is well known that these applications can fail to detect small lesions, particularly if they are located in the deep, retromandibular portion of the parotid gland or close to the stylomastoid foramen.9,10 Contrastenhanced MRI provides greater accuracy in identifying soft tissue lesions. Regarding parotid gland lesions, MRI provides excellent anatomic information about the topographic relationships between the skull base, soft tissues, and the facial nerve with the potential to distinguish benign and malignant lesions.11 The significance of facial nerve enhancement in patients with Bell’s palsy remains somewhat controversial. Gebarski et al12 showed asymmetric enhancement owing to the topography of the circum neural arteriovenous plexus even in patients without any clinical facial nerve pathologic features. In Bell’s palsy, several recent published reports have described contrast enhancement along the course of the facial nerve in MRI scans correlating with the areas of greatest edema and inflammation, as well as the prognosis.7,11,13 In contrast, other investigators have found no correlation
1828
MODERN IMAGING LIMITATIONS AND PAROTID CARCINOMA
FIGURE 2. A, B, Sections of transversal native short T1-weighted inversion recovery 5-mm MRI sequences, including intratemporal region. White arrow highlights different signal intensity due to shim artifact on MRI scan. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
FIGURE 3. A, B, Transverse, gadopentetate-enhanced, T1-weighted MRI slices. Other than susceptibility artifact (white arrow), no tumorous lesion was detectable. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
1829
GRIMMINGER ET AL
FIGURE 4. F-18-FDG PET scan with 370 MBq showing physiologic distribution of activity without signs of focal pathologic accumulation in area of head, skull base, and neck. Grimminger et al. Modern Imaging Limitations and Parotid Carcinoma. J Oral Maxillofac Surg 2011.
among the enhancement intensity, location, and recovery.14 The sensitivity, specificity, and accuracy in detecting malignant parotid lesions using contrast-enhanced MRI has been reported to be 87%, 94%, and 93%, respectively.5 However, acapsular tumors with atypical growth characteristics, such as diffuse infiltration of the surrounding tissues, such as was seen in the present case, might be undetectable using MRI. F-18-FDG-PET can be used to detect malignant tumors of various regions, and its usefulness in the differentiation of parotid gland lesions has been examined in several studies. Malignant parotid tumors showed significantly greater F-18-FDG uptake than either benign tumors or inflammatory lesions.15,16 Adams et al17 reported that PET has the greatest sensitivity and specificity for detecting lymph node metastases of head and neck
cancers compared with computed tomography, ultrasonography, and MRI. However, other investigators reported limitations of F-18-FDG-PET in the evaluation of parotid tumors because of a relatively high rate of false-positive results of about 30% owing to the high F-18-FDG uptake in benign tumors, such as cystadenolymphoma, pleomorphic adenoma, and oncocytoma.15,16 These specific considerations could explain the difficulties in the interpretation of F-18-FDG-PET results in parotid gland lesions. However, false-negative results are rare and have primarily been found in cases of small-size tumors.18 In conclusion, even if modern imaging techniques do not detect pathologic lesions, we suggest surgical facial nerve exploration in patients lacking signs of regeneration 6 to 8 months after the onset of the
1830 paralysis or with evidence of neuronal denervation by electromyography. Despite the progress of modern imaging techniques, this case report highlights that surgeons should be aware of the limitations of modern imaging techniques.
References 1. May M, Klein SR: Differential diagnosis of facial nerve palsy. Otolaryngol Clin North Am 24:613, 1991 2. Santos-Lasaosa S, Pascual-Millan LF, Tejero-Juste C, et al: [Peripheral facial paralysis: Etiology, diagnosis and treatment]. Rev Neurol 30:1048, 2000 3. May M, Hardin WB: Facial palsy: Interpretation of neurologic findings. Laryngoscope 88:1352, 1978 4. Jungehuelsing M, Sittel C, Fischbach R, et al: Limitations of magnetic resonance imaging in the evaluation of perineural tumor spread causing facial nerve paralysis. Arch Otolaryngol Head Neck Surg 126:506, 2000 5. Paris J, Facon F, Pascal T, et al: Preoperative diagnostic values of fine-needle cytology and MRI in parotid gland tumors. Eur Arch Otorhinolaryngol 262:27, 2005 6. Rumboldt Z, Gordon L, Bonsall R, et al: Imaging in head and neck cancer. Curr Treat Options Oncol 7:23, 2006 7. Freije JE, Harvey SA, Haberkamp TJ: False-negative magnetic resonance imaging in the evaluation of facial nerve paralysis. Laryngoscope 106:239, 1996 8. Jackson CG, Glasscock ME III, Hughes G, et al: Facial paralysis of neoplastic origin: Diagnosis and management. Laryngoscope 90:1581, 1980
MODERN IMAGING LIMITATIONS AND PAROTID CARCINOMA 9. Gosepath K, Hinni M, Mann W: The state of the art of ultrasonography in the head and neck. Ann Otolaryngol Chir Cervicofac 111:1, 1994 10. Weber AL: Imaging of the salivary glands. Curr Opin Radiol 4:117, 1992 11. Murphy TP, Teller DC: Magnetic resonance imaging of the facial nerve during Bell’s palsy. Otolaryngol Head Neck Surg 105:667, 1991 12. Gebarski SS, Telian SA, Niparko JK: Enhancement along the normal facial nerve in the facial canal: MR imaging and anatomic correlation. Radiology 183:391, 1992 13. Yetiser S, Kazkayas M, Altinok D, et al: Magnetic resonance imaging of the intratemporal facial nerve in idiopathic peripheral facial palsy. Clin Imaging 27:77, 2003 14. Engstrom M, Thuomas KA, Naeser P, et al: Facial nerve enhancement in Bell’s palsy demonstrated by different gadolinium-enhanced magnetic resonance imaging techniques. Arch Otolaryngol Head Neck Surg 119:221, 1993 15. Uchida Y, Minoshima S, Kawata T, et al: Diagnostic value of FDG PET and salivary gland scintigraphy for parotid tumors. Clin Nucl Med 30:170, 2005 16. Schmidt M, Schmalenbach M, Jungehulsing M, et al: 18F-FDG PET for detecting recurrent head and neck cancer, local lymph node involvement and distant metastases: Comparison of qualitative visual and semiquantitative analysis. Nuklearmedizin 43:91, quiz 2, 2004 17. Adams S, Baum RP, Stuckensen T, et al: Prospective Comparison of 18F-FDG PET with Conventional Imaging Modalities (CT, MRI, US) in lymph node staging of head and neck cancer. Eur J Nucl Med 25:1255, 1998 18. McGuirt WF, Keyes JW Jr, Greven KM, et al: Preoperative identification of benign versus malignant parotid masses: A comparative study including positron emission tomography. Laryngoscope 105:579, 1995