Focal pulmonary interstitial opacities adjacent to the thoracic spine osteophytes among the cases with right side aortic arch. Poster No.:
C-0977
Congress:
ECR 2015
Type:
Scientific Exhibit
Authors:
R. Yoshida, T. Yoshizako, H. Kitagaki; Izumo/JP
Keywords:
Lung, Musculoskeletal spine, CT, Normal variants, Atelectasis
DOI:
10.1594/ecr2015/C-0977
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Aims and objectives Osteophyte formation of the vertebral body is a very common change that occurs with age (1-4). The 80% of men at 50 years of age or older, more than 60% of women are said to have this change (1-4). And more, it is said that there is not thoracic osteophytosis in the area adjacent to the aorta on Chest CT (5). Otake, et al. said that the osteophytes of the thoracic vertebrae appear to cause focal fibrosis in the sub-pleural region of the lower lobe of the right lung (6). And they speculated that focal fibrosis might form in the left lung in the case that the osteophyte developed on the left side because of the rightward elongation of the descending aorta (6). We decided to confirm their predictions. The purpose of this study was to ensure whether thoracic osteophytes were seen on the left side anterior to the vertebrae on the Chest CT and evaluate the factors forthe focal pulmonary interstitial opacities adjacent to thoracic spine osteophytes, among the cases with right side aortic arch that the descending aorta is located in right front of the thoracic vertebrae.
Methods and materials #Patients Our Institutional Review Board approved this retrospective study and waived the need for informed consent from the patients. We retrospectively searched the hospital information system and the radiology information system in our hospital for the cases of patients withthediagnosis ofthe right side aortic arch, including Situs inversus viscerum, and received the Chest CTbetween 2003 April and 2014 September. We excluded patients whose age at the time of the Chest CT was less than 50 years old. And more, we excluded patients who did not have the thoracic spine osteophytes. We found the cases of22 patients (12 male, 10 female) with the right side aortic arch, including 5 cases of Situs inversus viscerum, withthoracic spine osteophytes and over 50 years old, received a chest CT (median age, 70 years; range, 52-82 years old). (Figure 1, Table 1). #CT Technique Chest CT was performed with the various scanners (GE CT9800, SIEMENS SOMATOM PLUS40, TOSHIBA Aquilion 16, PHILIPS Brilliance CT40, PHILIPS Brilliance CT64, TOSHIBA Aquilion ONE, TOSHIBA Aquilion CX). The CT images of the entire lungs were produced with the various thickness, depending on the time, such as 10-mm section thickness between 2003 and 2004, 7-mm section thickness between 2003 and 2004 and 5-mm section thickness since 2006. Lung window images were reconstructed with a highfrequency algorithm (width, 1600 HU;level, -600 HU).
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#Image Interpretation We reviewed CT scans, evaluated the following the factors, such as the position of thoracic osteophytes (left side, right side and both sides as a boundary the midline of the vertebral body), and the thickness of the thoracic osteophytes (Figure 2), the angle of the heart and the vertebral body (Figure 2), the presence or absence of focal pulmonary opacity adjacent to osteophyte. How to measure the thickness of the thoracic osteophytes and the angle of the heart and the vertebral body was shown in Figure 2. In order to measure the angle of the heart and the vertebral body, we decided three point, 1; the vertex of the osteophytes, 2; the point that the left lower lobe entered the innermost and 3; the intersection from 2nd point to the heart in the same cross section as osteophytes. If the patient had many thoracic osteophytes, we assumed the thickest osteophyte adjacent to the lung field as the representative. In the case with the focal pulmonary opacity adjacent to osteophytes, we evaluated the thickness of the focal interstitial opacity and sub-categorized the type of opacity such as reticular and liner shadow. #Statistical analysis Depend on the presence or absence of lung shadows, we divided into two groups, osteophyte with the pulmonary opacity group (group A) and osteophyte without the pulmonary opacity group (group B). The above-mentioned variables were compared between the two groups using Mann-Whitney U-tests for numeric values and the chisquared test for categoricalvalues. In both analyses, a P value of <0.05 was taken as indicating statistical significance. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS), version 22.0 for Windows, IBM, Japan. Images for this section:
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Fig. 1: Figure 1; Flow chart of patients' selection
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Fig. 4: Table 1
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Results #Clinical Findings The clinical findings on 22 patients with right side aortic arch are summarized in Table 1. Focal interstitial opacities in the sub-pleural region adjacent to the osteophytes of the lower lobe of the left lung were shown in 10 (45.5%; Group A) of the 22 cases. The Group A and Group B, these two group characteristics are summarized in Table 1. Five of these patients had Situs inversus viscerum. #CT Findings During the follow-up period, Chest CT was performed 1-11 times for each patient (average, 4 times). Table 2 shows CT findings between group A and group B. Twenty cases (90.9%) had the thoracic osteophytes on the left side, 2 cases (9.1%), both sides anterior to the vertebra. In the osteophyte with the pulmonary opacity group (group A, n=10), their pulmonary opacity were in the left lung on the opposite side of the thoracic descending aorta. Between the 2 groups, the presence of the pulmonary opacities associated with the thickness of osteophytes significantly (Mann-Whitney Utest, P <0.05), there was no significant difference in the distribution of age (Mann-Whitney U-test, P=0.821), gender and the angle of the heart and the vertebral body (MannWhitney U-test P=0.059). Situs inversus viscerum had been often to have the significance of the group A (chi-squared test, P <0.05). The representative examples are shown in Figures 2 and 3. Discussion Right aortic arch is one of the rare congenital abnormalities of the aortic arch among adults about 0.01%. Regardless of that rare occurrence, we sometimes encountered in the clinical situation(7-14). Goldberg, et al. reported that there is no ostetophyte at the site which is in contact with the aorta on CT (5). Considering about1978's of CT technology and the resolution, small osteophytes are expected not to be evaluated in size. However, their result will show the tendency that thoracic osteophytes are seen on the left side anterior to the vertebrae on Chest CT among the cases with the descending aorta which is located in right front of the thoracic spine. In our study, most of the osteophytes were found on the left side of the lower thoracic vertebrae. Our study was a result to support those reports. Our study has 2 cases with the osteophytes which located on the both sides of the vertebra. Their small osteophytes existed in the area adjacent to the aorta, although it did not reach the aorta (Fig.3). Consequently, focal pulmonary opacities were noted in the left lung. Our results were exactly that Otake,et al expected (6).
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This limited abnormalities that Otake,et al reported the pulmonary interstitial opacity adjacent to the thoracic osteophyte do not appear to progress and should not be considered a preclinical form of more extensive fibrosing lung disease (15). The phenomenon of fibrosis adjacent to spinal osteophytes in older individuals is seen as localized ground-glass opacity or reticular pattern adjacent to osteoarthritis protrusions and is easily recognized (15). These reports will mean that the pulmonary opacity adjacent to the osteophytes is one of the famous findings as the pseudo-lesions for radiologists to know on chest CT. In the case of right aortic arch that the descending aorta, which is located in right front of the thoracic spine, it will be necessary for us to also know that pulmonary opacity adjacent to osteophyte in the left lung. Whether or not there were the pulmonary opacities adjacent to thoracic spine osteophytes associated with the thickness of the osteophyte significantly. It was similar to the previous reports (6). Otake, et al showed that the histologic findings of the focal pulmonary opacity were focal pulmonary fibrosis due to the compression of the osteophytes. Among the cases with right side aortic arch, the focal pulmonary opacities adjacent to the osteophytes would be expected to be same histologic findings. Limitations The limitations of this study are the small number of cases derived from the right side aortic arch and Situs inversus viscerum as the rare congenital abnormalities. Images for this section:
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Fig. 2: Figure 2; Methods of measuring the osteophytes 74 year-old man in Group A (osteophyte with the pulmonary opacity group). The osteophyte located on the left side. The thickness of the osteophyte (two-headed arrow) and pulmonary opacity (reticular type) were 6mm. The angle that 2 dotted lines create was 63 degrees.
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Fig. 3: Figure 3; Case presentation of the osteophytes located on the both sides 72 yearold man in Group B (osteophyte without the pulmonary opacity group).The osteophytes located on the both sides of the vertebrae.
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Fig. 5: Table 2
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Conclusion Among the cases with the right-sided aortic arch, most of the thoracic osteophytes were seen on the left side anterior to the vertebrae, the presence of the pulmonary opacities adjacent to thoracic spine osteophytes associated with the thickness of the osteophyte.
Personal information References 1. 2. 3. 4. 5. 6. 7. 8.
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