Objective: To clarify the panoramic radiographic features of the post-Caldwell-Luc maxillary sinus. Methods: The panoramic radiographs were compared with the ...
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Dentomaxillofacial Radiology (2000) 29, 280 ± 285 2000 Macmillan Publishers Ltd. All rights reserved 0250 ± 832X/00 $15.00 www.nature.com/dmfr
Comparison of the panoramic radiographic and CT features of post-Caldwell-Luc maxillary sinuses T Ohba*,1, Y Morimoto1, Y Nagata1, T Tanaka1 and S Kito1 1
Department of Dental Radiology, Kyushu Dental College, Kitakyushu, Japan
Objective: To clarify the panoramic radiographic features of the post-Caldwell-Luc maxillary sinus. Methods: The panoramic radiographs were compared with the axial CT scans of 48 symptomatic post-Caldwell-Luc maxillary sinuses which had been operated on more than 5 years previously. Results: The two characteristic features of the post-Caldwell-Luc maxillary sinus on panoramic radiographs were a right-angled triangular shape, due to absence of the ¯oor of the maxillary sinus and radiopacity of the posterior wall and zygomatic bone, and an ill-de®ed panoramic innominate line. This shape was related to the ®nding of a contracted sinus with a radiolucent lumen on the CT scans. There was also close relationship between the ill-de®ned panoramic innominate line and thickened posterior wall on the CT scans. Conclusion: The characteristic features of the post-Caldwell-Luc maxillary sinus on panoramic radiographs were a right-angled triangular shape and an ill-de®ned panoramic innominate line. These features were related to a contracted sinus and a thickened posterior wall on the CT scans. Keywords: radiography, panoramic; tomography, X-ray computed; maxillary sinus; maxillary sinusitis
Introduction The Caldwell-Luc procedure was developed concurrently by George Caldwell in the US and Henri Luc in France in the 1890s.1,2 This procedure aords a means of access to the infected maxillary sinus and allows for the inspection, diagnosis and treatment of maxillary sinus disease. The main radiological appearances after a Caldwell-Luc procedure are antral radiopacity and contraction and thickening of the bony walls.3,4 These features have been described on both plain ®lms and CT scans.1,2,5 The appearance of the post-Caldwell-Luc maxillary sinus on panoramic radiographs has not been reported.
*Correspondence to: T Ohba, Department of Dental Radiology, Kyushu Dental College, 2-6-1 Manazuru, Kokura-kita-ku, Kitakyushu 803-8580, Japan Received 24 December 1999; accepted 23 May 2000
The purpose of our study was to clarify the panoramic radiographic features of surgically treated maxillary sinuses by comparison with the CT ®ndings. Materials and methods This study was based on 48 pairs of panoramic radiographs and CT scans which were obtained at the Department of Dental Radiology in Kyushu Dental College Hospital between 1993 and 1996 from patients with recurrent maxillary sinus disease who had undergone a bilateral Caldwell-Luc operation more than 5 years previously. These were 26 males and 22 females ranging in age from 23 to 84 years (mean: 53.6 years). Forty-three patients had had the procedure more than 20 years previously, the other ®ve patients less than 20 years, with an average of 31.5 years. The two sets of images were assessed independently by a single, experienced dental radiologist (TO) for the
Post-Caldwell-Luc maxillary sinus T Ohba et al
shape and pattern of the maxillary sinus and the appearance of panoramic innominate line was also evaluated. The results were classi®ed and then reviewed by four other dental radiologists. Results A. Features of the post-Caldwell-Luc maxillary sinus on panoramic radiographs The post-Caldwell-Luc maxillary sinuses were classi®ed into four shapes as shown in Figure 1. Shape I (Figure 1a) was a right-angled triangle (arrows), which was caused by the absence of the ¯oor of the maxillary sinus plus radiopacity of the posterior wall and zygomatic bone. Shape II (Figure 1b) was the same as Shape I, except that the ¯oor of the maxillary sinus was still present (arrow heads). Shape III
(Figure 1c) was also a right-angled triangle, but accompanied by a radiolucency of the posterior wall (arrows) and zygomatic bone areas (arrow heads). Shape IV (Figure 1d) was similar to Shape III, except that the ¯oor of maxillary sinus was present (arrow heads).
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Table 1 Distribution of the shape of the post-Caldwell-Luc maxillary sinuses on panoramic radiographs of 48 patients. For details of the shapes see Results, Section A Shapes I II III IV Others Total
a
b
c
d
No. of cases (%) 16 9 8 9 6 48
(33) (19) (17) (19) (12) (100)
Figure 1 The four shapes of the post-Caldwell-Luc maxillary sinus seen on panoramic radiographs. (a) Shape I, (b) Shape II, (c) Shape III, and (d) Shape IV. For details see Results, Section A Dentomaxillofacial Radiology
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Pattern D. Forty-®ve (94%) had thickening of the posterior wall (arrows) (Figure 5).
Figure 2 Panoramic radiograph showing an ill-de®ned innominate line in the right maxillary sinus (arrows)
The distribution of the shape of the 48 maxillary sinuses is shown in Table 1. There were 16 cases of Shape I of which 15 (94%) had had the operation more than 20 years previously. In contrast one-third of the nine cases of Shape IV had had the operation less than 20 years previously. When the appearance on the panoramic innominate line was assessed, 35 (73%) were ill-de®ned (Figure 2), while the other 13 (27%) were clearly visible. Eleven (85%) of the latter were thickened. Thirty-six (75%) cases had a well-de®ned image of the posterior wall of the sinus. Sixteen (44%) of these were ¯attened, 13 (36%) depressed and the remainder (20%) normal in shape. B. Internal consistency and structure on CT The consistency of the maxillary sinus was classi®ed into ®ve patterns as shown in Figure 3. Pattern A (Figure 3a) was homogeneous and slightly higher in density than the inferior nasal concha. Pattern B (Figure 3b) was heterogeneous and higher in density than the inferior nasal concha. Pattern C (Figure 3c) was similar in density to Pattern B but accompanied by a large amount of soft-tissue, which was similar in density to the inferior nasal concha. Pattern D (Figure 3d) was similar in density to Pattern C except that it contained air in the centre (*). Pattern E (Figure 3e) resembled Pattern B except that it also contained air (*). The distribution of the pattern of internal structure is shown in Table 2. Thirty-eight per cent of maxillary sinuses were Pattern B and all of them had had the operation more than 20 years previously. Two of the 18 cases in Patterns A and C had had the operation less than 20 years previously. Forty-four (92%) of the 48 sinuses showed a marked contraction (Figure 4), due mainly to depression of the anterior (arrows heads) and medial (arrows) walls. The nasal cavity was widened due to the depression of the medial wall. Eleven (23%) contained air, including six of Pattern E and two of Dentomaxillofacial Radiology
C. Comparison of the features of the post-Caldwell-Luc maxillary sinus between panoramic radiographs and CT scans Table 3 shows the comparison of the sinus ¯oor and innominate line on panoramic radiographs and the density of the maxillary sinus on CT scans in Pattern A and B. Fifteen of the 27 ¯oors of the maxillary sinus could not be seen on panoramic radiographs and 11 (73%) of these cases were associated with a heterogeneous sinus on the CT scans. In the 12 cases when the ¯oor could be seen, seven (58%) had a heterogeneous sinus. Twenty of the 27 panoramic innominate lines were ill-de®ned and 14 (70%) of the cases had a heterogeneous sinus. A clear panoramic innominate line was found in seven cases of which four were heterogeneous in density. Table 4 compares the panoramic appearance of the innominate line and the CT appearance of the posterior wall. Thirty-®ve (73%) of the 48 panoramic innominate lines were ill-de®ned and 34 (97%) had a thickened posterior wall on CT. The remaining 13 were clearly visible and nine (69%) had a thickened posterior wall. Discussion Noyek and Zizmor3 showed that approximately onethird of post-Caldwell-Luc maxillary sinuses were radiopaque on plain ®lms. They also found a variable degree of thickening of the bony wall. Unger et al.2 further described a contracted antrum in postCaldwell-Luc maxillary sinuses. We found that mucosal thickening was accompanied by sclerosis of the bony walls as the Pattern D (see Results, Section C) on CT. Furthermore, the contracted maxillary sinus, after the Caldwell-Luc procedure, was related to the right-angled triangular shape seen on panoramic radiographs. We believe this is caused by the characteristic projection angle of the X-ray beam through the depressed anterior and medial walls of the contracted sinus (Figure 6). The radiolucency seen on the panoramic radiographs is due to the superimposition of a wide nasal cavity on a depressed medial and anterior walls. The absence of the ¯oor is due to ®bro-osseous proliferation. The contents of the maxillary sinus on the CT scans were classi®ed as either homogeneous, heterogeneous or a combination with air or soft-tissue density consistency. Unger et al.2 mentioned that changes seen after the Caldwell-Luc procedure are due to ®bro-osseous proliferation which may produce either a thickening of the antral wall or totally obliterate the lumen. In our study, proliferation of the ®brous tissue was seen as homogeneous, as in Pattern A, and the
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a
b
c
d
e
Figure 3 Five patterns of density of the post-Caldwell-Luc maxillary sinus lumen on CT. (a) Pattern A, (b) Pattern B, (c) Pattern C, (d) Pattern D, and (e) Pattern E. For details see Results, Section B Dentomaxillofacial Radiology
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Table 2 Distribution of the pattern of internal structure of the postCadwell-Luc maxillary sinuses on axial CT of 48 patients. For definition of the patterns see Results, Section B Patterns A B C D E Others Total
No. of cases (%) 9 18 9 2 6 4 48
(19) (38) (19) (4) (12) (8) (100)
Table 3 Comparison of the floor of the maxillary sinus and the innominate line on panoramic radiographs with the density of the maxillary sinus on axial CT in 27 cases of the post-Cadwell-Luc maxillary sinus Panoramic radiographs
CT scans Pattern A Pattern B (Homogeneous) (Heterogeneous)
Sinus floor Not evident Evident
4 5
11 7
Innominate line Ill-defined Well-defined
6 3
14 4
Table 4 Comparison of appearance of the panoramic innominate line and posterior wall of 48 cases of the maxillary sinus on axial CT 2
Panoramic innominate line Ill-defined Well-defined
Present 34 9
Posterior wall Thickening
Absent 1 4
An
Figure 4 Axial CT scan showing a contracted left maxillary sinus accompanied by a heterogeneous lumen (Pattern B). The right maxillary sinus is symptomatic due to a postoperative maxillary cyst (*) Pa Po
Figure 6 Schematic drawing of the projection of an X-ray beam in relation to the maxillary sinus in panoramic radiography. An=anterior surface of the maxillary sinus; Pa=panoramic innominate line; and Po=posterior surface of the maxillary sinus
Figure 5 Axial CT scan showing a thickened posterior wall of the right maxillary sinus accompanied by a heterogeneous lumen. The left maxillary sinus contains a postoperative maxillary cyst (*)
®bro-osseous reaction as heterogeneous, as in Pattern B. It also seemed that the ®bro-osseous proliferation increased in relation to the length of time after the Caldwell-Luc procedure. Ill-de®ned or thickened panoramic innominate lines are characteristic of the post-Caldwell-Luc maxillary sinus on panoramic radiographs. Seventy-three per Dentomaxillofacial Radiology
cent of the innominate lines were ill-de®ned in the study. Of those, the most were related to a thicknened posterior wall and a heterogeneous sinus on CT scans. Bony thickening usually occurs in the posterolateral wall of the post-Caldwell-Luc maxillary sinus.1 The resulting status of the panoramic innominate line, which depends on the angle of the X-ray beam to the posterior surface of the zygomatic process6 (see Figure 6), and may be in¯uenced by such changes. A ¯attened or depressed posterior wall of the maxillary sinus is also characteristic of post-Caldwell-Luc maxillary sinuses on panoramic radiographs. Eighty
Post-Caldwell-Luc maxillary sinus T Ohba et al
per cent of the posterior walls were ¯at or depressed in this study. Hypoplasia of the maxillary sinus is uncommon.7,8 However, it is dicult to dierentiate radiographically developmental hypoplasia from that which is secondary to surgery.7 Hypoplastic maxillary sinuses have the same features on both panoramic radiographs and CT scans.
In conclusion, this study has clari®ed the characteristic features of post-Caldwell-Luc maxillary sinuses on panoramic radiographs, the right-angled triangular shapes and ill-de®ned panoramic innominate line. These features are related to a contracted sinus and a thickened posterior wall on CT.
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References 1. Cable HR, Jeans WD, Cullen RJ, Bull PD, Maw AR. Computerized tomography of the Caldwell-Luc cavity. J Laryngol Otol 1981; 95: 775 ± 783. 2. Unger JM, Dennison BF, Duncavage JA, Toohill RJ. The radiological appearance of the post-Caldwell-Luc maxillary sinus. Clin Radiol 1986; 37: 77 ± 81. 3. Noyek AM, Zizmor J. Radiogy of the maxillary sinus after Caldwell-Luc surgery. Otolaryngol Clin North Am 1976; 9: 135 ± 151. 4. Dolan KD, Smokerw WRK. Paranasal sinus radiology, Part 4B: Maxillary sinuses. Head Neck Surgery 1983; 5: 428 ± 446.
5. Zanella FE, Brusis T, MoÈdder U. High-resolution computer tomography of osseous changes following radical operation of the maxillary sinuses. Laryngol Rhinol Otol (Stuttg) 1986; 65: 74 ± 78. 6. Katayama H, Ohba T, Ogawa Y. Panoramic innominate line and related roentgen anatomy of the facial bones. Oral Surg Oral Med Oral Pathol 1974; 37: 131 ± 137. 7. Yanagisawa E, Smith HW. Normal radiographic anatomy of the paranasal sinuses. Otolaryngol Clin North Am 1973; 6: 429 ± 457. 8. Radecki CA, Mintz SM. Maxillary antrum hypoplasia. Report of a case. Int J Oral Maxillofac Surg 1990; 19: 158 ± 159.
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