Olfactory Neuroblastoma: MR Evaluation

Transcription

1 Olfatory Neuroblastoma: MR Evaluation Cheng Li,I.2.3 David M. Yousem,I.2.3 Rihard E. Hayden,2 and Rihard L. Dotyl.2 PURPOSE: To evaluate MR in the diagnosis and staging of olfatory neuroblastoma. METHODS: Five patients with histologially proved olfatory neuroblastomas were studied by MR. Four also had CT sans. RESUL TS: The extent of disease delineated by MR agreed with surgial findings and surgial staging of the tumor in all five patients. All ases of olfatory neuroblastomas originated in the nasal and involved the ethmoid sinuses. In three of the five ases, the tumors extended to the anterior skull base. In one ase MR orretly suggested skull base involvement missed on CT. Lesions were isointense to hyperintense with musle on Tl-weighted sans. Compared with fat on T2-weighted sans, olfatory neuroblastomas were variable in signal intensity. Enhanement was minimal to moderate in all ases. CONCLUSION: In the evaluation of olfatory neuroblastoma, MR is most useful in delineating the extent of the tumor and may be more aurate than CT. However, the signal intensity harateristis of olfatory neuroblastomas may overlap other tumors. Index terms: Neuroblastoma; EsthesioneurobIastoma; Nose, neoplasms; Nose, magneti resonane AJNR 14: , Sep/Ot 1993 Olfatory neuroblastoma (ON), also alled esthesioneuroblastoma, is an unommon intranasal tumor originating from the olfatory neuroepithelium lining the roof of the nasal vault and in lose proximity to the ribriform plate. ONs our in all age groups with a peak inidene in the age groups of 11 to 20 years and 51 to 60 years (1). There is a slightly greater inidene of the tumor in women. The ommon linial symptoms are nasal obstrution, reurrent epistaxis, hyposmia, rhinorrhea, headahes, and visual disturbanes (1-4). Computed tomography (CT) has been shown to be extremely useful in staging and treatment planning of this tumor (2, 5). However, magneti resonane (MR) imaging has shown tremendous promise in surpassing CT for the mapping of neoplasms of the nasal and paranasal sinuses (6-9). The authors have enountered five patients with histologially proved Reeived June 22, 1992; revision requested August 31, reeived September 24, and aepted November 10. Supported in part by NIDCD grant Pol DC (to Rill). I Smell and Taste Center, 2Department of Otorhinolaryngology and Head and Nek Surgery, and 'Department of Radiology, Hospital of the University of Pennsylvania, 3400 Sprue St, Philadelphia, PA Address reprint requests to David M. Yousem, MD. AJNR 14: , Sep/Ot Amerian Soiety of Neuroradiology 167 ON during the past 5 years who had MR studies. This entity has not been well desribed in the MR literature, and it remains to be seen whether ONs have stereotypial MR imaging features that an distinguish ON from other lesions. Materials and Methods Five patients with histologially verified ONs were examined by MR (n = 5} and CT (n = 4}. There were three women and two men with ages ranging from 17 to 76 years (mean 49.4 years} (see Table 1}. MR imaging was performed on a General Eletri (Milwaukee, WI} 1.5- T Signa sanner using the quadrature head oil and a Medial Advanes (Milwaukee, WI} anteriorposterior volume nek oil. T1-Weighted images were performed in the axial, oronal, and/or sagittal plane, /11-30/1-2 (repetition time/eho time/exitations}. Double-eho long- TR sans ( /18-25} were performed in the axial plane. In three of the five ases, gadopentetate dimeglumine (Berlex Industries, Wayne, NJ} was administered at a dose of 0.1 mmol/kg. T1-weighted sans (with the idential parameters above} were performed immediately after administration of the gadolinium in the axial and oronal planes. Fat-suppression tehniques for the postontrast sans were variably employed. All MR sans used a 256 X 192 matrix, 5-mm-thik setions, and inferior saturation pulses. Intersetion gaps of 2 to 2.5 mm were standard for long- TR sans; the short- TR sans had no intersetion gaps.

2 1168 LI AJNR: 14, September/Otober 1993 TABLE 1: Clinial information in five patients with olfatory neuroblastoma 76, F Nasal obstrution, dereased smell, headahe Right upper nasal 2 65, F Epistaxis, nasal Left upper nasal B obstrution 44, M Dereased smell and Left upper nasovision on left pharynx 4 17, F Nasal ongestion, Right sinonasal B right > left 5 45, M Epistaxis Left upper nasal CT was performed on a GE 9800 sanner. Three- to 10- mm-thik setions were obtained in both the axial and oronal planes, after administration of intravenous ontrast material. Supplementary 5-mm sans were made through regions of speial interest. Both the MR and CT sans were arefully evaluated for the tumor's original loation, extension, bony struture hanges, anterior skull base invasion, and some assoiated hanges, inluding postobstruted seretions, hemorrhage, and edema. ONs were staged from A to C aording to the lassifiation system developed by Kadish et a! (2). In stage A, the tumor is limited to the nasal. In stage B, the tumor is onfined to the nasal and paranasal sinuses, and in stage C, the tumor extends beyond the nasal and paranasal sinuses. The sans were retrospetively reviewed by two radiologists in onert without knowledge of surgial findings. The CT and MR sans were viewed separately but one after the other in a random order. The CT and MR sans were performed within 1 to 13 days of eah other with no intervening therapy. The imaging findings were ompared with surgial findings. Fig. 1. Case 1. Seventy-six-year-old woman with reported hyposmia and pathologially onfirmed olfatory neuroblastoma. A, Sagittal (600/20) MR san through the midline demonstrates a soft-tissue mass (arrow) whih breahes the ribriform plate and demonstrates extra axial intraranial tumor (arrowheads). B, Axial (3000/90) MR san through the same level demonstrates persistent low signal intensity of the mass. Note the high signal intensity (arrowhead) of obstruted seretions in the posterior ethmoid air ell behind the lesion. C, Axial (3000/35) MR san through the level of the superior orbits demonstrates a low-intensity mass (arrow) within the right nasal and ethmoid air ells with extension aross midline to the left ethmoid air ells. D, Coronal (600/20) MR san through the anterior nasal demonstrates the intraranial extension of the mass (arrowhead) through the ribriform plate invading the region of the olfatory lobe on the right side. Postobstrutive seretions are present within the maxillary antrum (A). A B D

3 AJNR: 14, September/Otober 1993 OLFACTORY NEUROBLASTOMA 1169 A B Fig. 2. Case 2. Sixty-five-year-old woman with persistent epistaxis. Biopsy proved olfatory neuroblastoma. A, Axial CT san through the nasal after biopsy reveals a mass in the mid to posterior left nasal (arrow), whih is well defined on this image. The lower density anterior to the mass is aused by paking after the biopsy. B, Coronal (3500/90) MR san demonstrates the lower signal intensity of the nasal and medial left ethmoid sinus neoplasm, whih is differentiated from the high signal intensity of the lateral left ethmoid sinus obstruted seretions and the obstruted seretions in the left maxillary antrum. C, Coronal CT san fails to demonstrate a good differentiation between neoplasm and postobstruted seretions, pointing up one of the weaknesses of CT in the evaluation of neoplasti proesses in the paranasal sinuses. D, Axial postontrast 750/26 MR san through the lesion demonstrates the nonenhaning paking in the anterior portion of the left nasal and the enhaning tumor posterior to it ( t). MR with gadolinium may be useful in differentiating inflammatory from neoplasti onditions, beause inflammation enhanes in a peripheral fashion, whereas enhanement in neoplasms tends to be solid. D Results Clinial data on the patients with ON are summarized in Table 1. On Tl-weighted (short- TR, short- TE) MR examinations, all ONs were hypointense to fat, but the intensity ompared with musle and inflammatory muosal disease was variable. On T2- weighted (Iong- TR, long- TE) sequenes, the tumors were always hyperintense to musle and hypointense to inflamed muosa, but had variable intensity ompared with fat. On proton densityweighted (Iong- TR, short- TE) sans the five ONs were hypointense to fat, hyperintense to musle, and hypointense to muosal disease. Gadopentetate dimeglumine was administered to three patients. Tumor enhanement was heterogeneous in the three ases. In these three ases, the solid tumor enhanement was readily disernible from the peripheral (rim) enhanement of obstruted sinonasal seretions. Menin- geal invasion, or the lak thereof, was well demonstrated after gadolinium. Two tumors demonstrated spekled alifiations on CT sans; the alified portion of the mass was not deteted, even in retrospet, on MR sans. The extent of disease delineated by MR agreed with surgial findings in all five patients. Four ases of ON originated in the high nasal and involved the ethmoid sinus (Figs 1 and 2). In three of the five ases, tumors extended to the anterior skull base. One tumor invaded the brain and produed white matter edema (Fig 1 ). Another ase was unusual in that it involved the maxillary antrum more than the nasal (Fig 3). Although the staging by CT (in four ases) was equivalent to MR, MR demonstrated intraranial extension not apparent on CT in one ase. Why the intraranial extension by this ON was not

4 1170 LI AJNR: 14, September/Otober 1993 Fig. 3. Case 4. Seventeen-year-old girl with nasal stuffiness and pathologially proved olfatory neuroblastoma. A, Sagittal (600/20) MR san to the right of midline demonstrates a soft-tissue mass that ompletely opaifies the right nasal. Note the heterogeneity 9f the signal intensity within the mass with the anterior portion more hyperintense than the intermediate posterior portion. The bony margin of the ribriform plate (arrowheads) is intat, as surgially onfirmed. B, Axial (600/20) MR san through the maxillary antrum demonstrates omplete opaifiation of the maxillary antrum by the neoplasti proess ( 7). Whenever one onfronts an isolated maxillary sinus opaifiation, one should onsider neoplasm rather than an Inflammatory ondition. The bony margin of the maxillary antrum is breahed medially, as invasion into the nasal is evident. C, Coronal (2500/80) san further anterior to C demonstrates the low intensity of the mass, again isointense with gray matter. Although there is high signal intensity aused by postobstrutive seretions in the frontal-ethmoidal reess on the right side, no tumor is seen to Invade the ribriform plate or extend intraranially. MR Is exquisitely useful for differentiating neoplasm from postobstruted seretions beause of the differene in the signal intensity, as noted in this example. seen on CT was unlear but probably related to the very minimal destrution of the ribriform plate. The tumor may have traveled through the sieve-iike openings through the ribriform plate rather than aggressively destroying bone. Nonetheless, beause of onomitant orbital involvement, this ON was preoperatively labeled as stage C by both CT and MR. Therefore, although the staging was idential, the MR more aurately mapped the tumor, as was onfirmed at surgery. Disussion ONs are rare, slow-growing malignant tumors of the sinonasal. The inidene of ON has been estimated to range between 2% to 3% of all malignant intranasal neoplasms (4). Most of the ases of ON arise from the olfatory neuroepithelium lining the ribriform plate, upper onethird of the nasal septum, superior turbinates, and anterior ethmoid air ells. Symptoms assoiated with early ON inlude: 1) gradually dereasing sense of smell; 2) some degree of unilateral nasal obstrution; and 3) episodi epistaxis. These early linial symptoms are nonspeifi but, in ombination, should lead one to onsider the diagnosis of ON. The tumors tend to grow slowly, spread submuosally, and eventually extend into adjaent strutures, espeially the sinuses, palate, orbit, and brain. Remote metastases may our in advaned ases. The preoperative assessment of a patient with ON requires medial imaging, and herein lies some ontroversy. Although CT is superior to MR in the evaluation of bony strutures, softtissue boundaries between tumor, retained seretions, and musle are more aurately delineated with MR (9). Whih study should be ordered? In this short report, we found that MR was more aurate than CT in delineating ON extent. Beause the staging system is so general, the improved auray of MR in delineating the tumor is not demonstrated just by stage lassifiation. Extension to the orbit on one CT study led to a stage C lassifiation. The onomitant intraranial extension noted by MR was not seen on CT. Although this is not refleted by differenes in the staging lassifiation (stage C inludes both orbital and intraranial extension), the finding on MR made a differene in the surgial approah. A raniofaial (neurosurgialotorhinolaryngologi) ombined-team approah was neessary. We have noted this improved

5 AJNR: 14, September/Otober 1993 OLFACTORY NEUROBLASTOMA 1171 ability to detet intraranial spread by MR in a study of inverted papillomas (10). It would seem that intraranial spread need not require ribriform plate destrution detetable by CT. Perhaps a tumor an ross the fenestrations of the plate without destroying it to a degree detetable by CT. The ability of MR to differentiate tumors from obstruted seretions in the paranasal sinuses was evident in this study also and has been previously desribed with other sinonasal tumors (7). Obstruted seretions are generally (but not exlusively) high intensity on T2-weighted sans and show peripheral enhanement; tumors are usually (but not exlusively) intermediate in intensity on T2-weighted sans and enhane in a solid fashion. Gadolinium enhanement is therefore very helpful in the mapping of sinonasal neoplasms. Its utility in determining meningeal and extradural extrameningeal spread is widely known; it also an be helpful, in other settings, to detet perineural spread of sinonasal neoplasms. It should be noted that the signal-intensity harateristis of ONs in this limited study population overlap those of other neoplasms in the sinonasal (11). One of the distinguishing features of this tumor is its propensity for alifiation, although inverted papillomas and hondroid tumors an alify as well. Spin-eho MR is less sensitive for the detetion of alifiation than CT is. In this regard, CT findings may sug- gest the speifi histology of ON when there is a alified superior nasal mass. However, by virtue of the lesion's loation high in the nasal vault, the diagnosis of ON usually will be also suggested by MR. In any event, a biopsy is required for histopathologi onfirmation. At that point, the superior mapping ability of MR is of paramount importane. Referenes 1. Elkon D, Hightower SI, Lim Ml, et al. Esthesioneuroblastoma. Caner 1979;44: Kadish S, Goodman M, Wang CC. Olfatory neuroblastoma. A linial analysis of 17 ases. Caner 1976;37: O'Connor T A, Mlean P, Juilland GJF, et al. Olfatory neuroblastoma. Caner 1989;63: Anavi Y, Bahar M, Ben-Bassat M. Olfatory neuroblastoma: report of a ase and review of the literature. J Oral MaxilJofa Surg 1989;47: Hurst RW, Erikson S, Cail WS, et al. Computed tomographi features of esthesioneuroblastoma. Neuroradiology 1989;31: Woodhead P, Lloyd GA. Olfatory neuroblastoma: imaging by mag, neti resonane, CT and onventional tehniques. Clin Otolaryngol 1988;13: Shapiro MD, Som PM. MRI of the paranasal sinuses and nasal. Radiol Clin North Am 1989;27: Tassel PV, lee Y. Gd-DTPA enhaned MR for deteting intraranial extension of sinonasal malignanies. J Comput Assist Tomogr 1991;15: Paling MR, Blok WC, levine PA, et al. Tumor invasion of the anterior skull base: a omparison of MR and CT studies. J Comput Assist Tomogr 1987;11: Yousem DM, Fellows DW, Kennedy DW, et al. Inverted papilloma: MR evaluation. Radiology 1992;185: Som PM, Shapiro MD, Biller HF, Sasaki C, lawson W. Sinonasal tumors and inflammatory tissues: differentiation with MR imaging. Radiology 1988;167: