MR and CT anatomy and the pathology of skull base focusing on pterygopalatine fossa

Transcription

1 MR and CT anatomy and the pathology of skull base focusing on pterygopalatine fossa Poster No.: C-1688 Congress: ECR 2010 Type: Educational Exhibit Topic: Head and Neck Authors: S. Kandatsu, R. Kishimoto, T. Omatsu, J. Mizoe, T. Kamada; Chiba/JP Keywords: Pterygopalatine fossa, Foramen rotundum, Head and neck tumors DOI: /ecr2010/C-1688 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 23

2 Learning objectives The skull base is composed of several bones and has some openings, through which nerves or vessels pass. Tumors or infection tend to invade via the openings. The pterygopalatine fossa (PPF), which is located in the skull base, communicates with the middle cranial fossa via foramen rotundum, nasal cavity via sphenopalatine foramen, oral cavity via palatine foramen, foramen lacerum, and infra temporal fossa via pterygomaxillary fissure. Pterygopalatine ganglion is located in PPF with the branches of maxillary nerve and branches of maxillary vessels. Tumors in head and neck area sometimes extend intracranially as a result of perineural spread through branches of the fifth nerve. Because the PPF is a cleft-like space surrounded by several bones, CT scan is superior to MRI because of its thinner slice and detectability of bone abnormalities. MRI is superior to CT because of its high contrast and detectability of bone invasion. We have sometimes experienced the bony invasion without obvious abnormal bone findings on CT. We make fusion imaging of CT and MRI for taking an advantage of characters of both modalities. Background One of the possibilities of surgical resection of head and neck tumor depends on whether the tumor invades to skull base or not. Because of the complexity of skull base, diagnosis of invasion to skull base is significant in the treatment of the head and neck tumors. The most common direction of spread of nasopharyngeal tumor is anterior region of the skull base. The pterygopalatine fossa (PPF) is located in the boarder of anterior and middle part of the skull base and a common site for direct invasion and perineural spread of disease. The tumor in the PPF spreads unexpectedly far from the primary site along with nerves or vessels. In order to diagnose precisely the invasion of PPF, precise comprehension of the anatomy of this area is necessary. Imaging findings OR Procedure details Methods: CT: 16 channel MDCT mm collimation with 1mm reconstruction MR: 1.5 T unit. 4mm slice with 1 mm gap. Spin-echo sequences were used. Fusion workstation: Fuji Medical Vincent. Aze Virtual Place, Mirada Fusion 7D. Page 2 of 23

3 Objectives: 81 persons with invasion or break of PPF by malignant tumors. Pathology: Squamous cell carcinoma, adenoid cystic carcinoma, adeno carcinoma, acinic cell carcinoma, mucoepidermoid carcinoma, melanoma, chondrosarcoma, PNET, leiomyosarcoma, osteosarcoma, liposarcoma, solitary fibrous tumor, esthesioneuroblastoma, and MFH. Images for this section: Fig. 1: Fig 1 shows bony structure of skull base. The skull base is the inferior area of the skull and consists of five bones: Ethmoid, sphenoid, occipital, frontal, and temporal Page 3 of 23

4 bones. Because the skull base isolates brain from head & neck area and protect the brain from microorganism outside. If malignant tumor invades skull base, therapy by surgical resection is impossible. Malignant tumor or microorganism invades via any openings through which nerve or vessels pass. Fig. 2: Fig 2 shows anterior part of the skull. Arrow shows a bilateral pterygopalatine fossa. Pterygopalatine fossa is composed of three bones: sphenoid bone with sphenoid sinus, maxillary bone with maxillary sinus, and palatine bone. Ethmoid: Ethmoid bone. Frontal: Frontal bone. Sphenoid: Sphenoid bone Temporal: Temporal bone. Page 4 of 23

5 Fig. 3: Fig 3 shows CT anatomy of the PPF at some levels. 3-a shows upper part, 3-b shows upper middle part, 3-c shows lower middle part, and 3-d shows lower part. ETS: Ethmoid sinus MXS: Maxillary sinus PPF: Pterygopalatine fossa Page 5 of 23

6 Fig. 4: Fig 4 shows major four routes invading PPF. Type 1: from nasal space Type 2 : destruction of posterior wall of maxillary sinus, Type 3: perineural invasion along with branches of maxillary nerve Type 4: Others consist of from above orbital fissure or from caudal part of sphenoidal bone. Page 6 of 23

7 Fig. 5: Table 1 shows major four routes invading PPF. Type 1: from nasal space Type 2: destruction of posterior wall of maxillary sinus, Type 3: perineural invasion along with branches of maxillary nerve Type 4: Others consist of from above orbital fissure or from caudal part of sphenoidal bone. Page 7 of 23

8 Fig. 6: Fig 5 shows type I invasion of squamous cell carcinoma from nasal space. Fig 5-a CT imaging shows invasion via sphenopalatine foramen. The tumor invades cavernous sinus via foramen rotundum. Page 8 of 23

9 Fig. 7: 5-b. MR imaging shows nasal space tumor. The tumor invades cavernous sinus and extended laterally. Yellow arrows show cavernous sinus invasion and lateral spread. Page 9 of 23

10 Fig. 8: 5-c Fusion imaging shows broad bone invasion. Yellow arrow shows bone invasion. Green arrow shows cavernous sinus invasion. Page 10 of 23

11 Fig. 9: Fig 6 shows synovial sarcoma destructing posterior wall of maxillary sinus. 6-a shows type 2 invasion on CT imaging. Page 11 of 23

12 Fig. 10: 6-b shows MR imaging. Page 12 of 23

13 Fig. 11: 6-c shows fusion imaging. The fusion imaging shows distinctive relation of the tumor with adjoining bone structure. Page 13 of 23

14 Fig. 12: Fig 7 shows adenoid cystic carcinoma invading PPF along with infraorbital nerve, which is branch of maxillary nerve. The tumor invade vidian canal. 7-a shows type 3 invasion on CT imaging. Page 14 of 23

15 Fig. 13: 7-b shows MR imaging. Page 15 of 23

16 Fig. 14: 7-c shows fusion imaging. In the fusion imaging, yellow arrow shows PPF invasion and green arrow shows invasion of vidian canal. Page 16 of 23

17 Fig. 15: Fig8 shows adenoid cystic carcinoma. Adenoid cystic carcinoma invades PPF from caudal part of sphenoidal bone. Many adenoid cystic carcinomas have soft character with mild bone destruction. However, sometimes, the tumor develops aggressively with bone destruction. 8-a shows type 4 aggressive bone destruction on CT. Page 17 of 23

18 Fig. 16: 8-b shows invasion from lower part of sphenoid bone on coronal MR imaging. Page 18 of 23

19 Fig. 17: 8-c shows fusion imaging. The fusion imaging shows clear relation of PPF with tumor. Page 19 of 23

20 Fig. 18: Fig9 shows mistaken diagnosis of PPF invasion. 9-a shows depletion of fat tissue in the PPF, which suggests tumor invasion. Page 20 of 23

21 Fig. 19: 9-b shows staining of PPF on fat saturated T1 weighted MR imaging after contrast media infusion. Although PPF is stained after contrast media infusion, no invasion was detected. Fat depletion is due to inflammation induced by past radiation therapy. In order to distinguish inflammation by radiation therapy from invasion, detection of normal vessels, no bony destruction, and no dilatation of opening are necessary. In this case, vessels within the PPF are detected without dilatation of PPF. Page 21 of 23

22 Conclusion CT is superior to MR imaging in the diagnosis of PPF invasion by malignant tumor. But MRI has some advantage to CT. Fusion imaging of CT and MRI makes the precise diagnosis of this area. Personal Information Susumu Kandatsu. MD. References 1. Gullane PJ, Conley J. Carcinoma of the maxillary sinus. A correlation of the clinical course with orbital involvement, pterygoid erosion or pterygopalatine invasion and cervical metastases. J Otolaryngol 1983;12: Curtin HD, Williams R, Johnson J. CT of perineural tumor extension: pterygopalatine fossa. AJR Am J Roentgenol 1985;144: Slavin ML, Abramson AL. Squamous cell carcinoma of the pterygopalatine fossa (retroantral space). J Clin Neuroophthalmol 1986;6: Pandolfo I, Gaeta M, Longo M, et al. [Computed tomography of the pterygopalatine fossa. Normal anatomy and neoplastic pathology]. Radiol Med 1988;76: Hofmann E, Wimmer B. [The anatomy of the pterygopalatine fossa in CT]. Rofo 1989;151: Chong VF, Fan YF, Khoo JB, Lim TA. Comparing computed tomographic and magnetic resonance imaging visualisation of the pterygopalatine fossa in nasopharyngeal carcinoma. Ann Acad Med Singapore 1995;24: Kim HS, Kim DI, Chung IH. High-resolution CT of the pterygopalatine fossa and its communications. Neuroradiology 1996;38 Suppl 1:S Daniels DL, Mark LP, Ulmer JL, et al. Osseous anatomy of the pterygopalatine fossa. AJNR Am J Neuroradiol 1998;19: Page 22 of 23

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