Paranasal Sinus Findings in Children During Respiratory Infection Evaluated With Magnetic Resonance Imaging

Subjects

The subjects were recruited from child care centers in Oulu, a Finnish city with ∼120 000 inhabitants, during September to December 1999. The children participated in a trial to evaluate the effect of xylitol on the appearance of otitis media during an upper respiratory infection.⁴ The parents were asked to bring the child to the Department of Pediatrics, Oulu University Hospital, within 96 hours after the onset of any symptoms suggestive of respiratory infection. Children aged 4 to 7 years were offered a chance to participate in the present study. MRI was conducted within the next 7 days. The exclusion criteria were acute otitis or tonsillitis; chronic sinusitis or previous sinus surgery; poor cooperation, claustrophobia, and the presence of any implanted ferrous material. The parents were informed about the survey and gave informed consent. The Ethical Committee of the Medical Faculty of the University of Oulu found the study protocol ethically acceptable. Altogether, 60 symptomatic children (27 boys and 33 girls) were enrolled (Fig 1).

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Fig 1.

Study profile.

Background Data

The background information of the children obtained with a questionnaire are shown in Table 1. The occurrence and duration of acute symptoms were evaluated with modified criteria developed by Jackson et al.⁵ The severity of each symptom was graded on a scale from 0 (not present) to 4 (very severe) and summed up to get the total symptom scores.

MRI Examinations

MRI was performed with an open resistive 0.23 T MRI scanner (Marconi Medical Systems, Cleveland, OH) with a head surface coil including axial and coronal T2-weighted (TR 4300 ms, TE 126 ms) fast-spin echo images with a 4-mm slice thickness.

The gradings of the paranasal sinuses were done as described earlier^6,7 with some modifications: grade 0, ≤2 mm mucosal thickening; grade 1, >2 mm mucosal thickening, one third volume loss; grade 2, one third to two thirds volume loss; and grade 3, more than two thirds volume loss or air-fluid level. The final grade for each sinus was determined from the more severely affected side, and each grade was summed up to get the total MRI scores (range: 0–24). Grade 0 and undeveloped sinuses were recorded as a normal finding, grade 1 as minor abnormality, and grades 2 to 3 as major abnormality. One radiologist (E.I.) and 1 otorhinolaryngologist (A.K.) interpreted the MRI scans blinded to the clinical data.

Follow-up Examination

In case of major abnormality in the maxillary sinus on the initial MRI scan, the child was offered the possibility of a follow-up scan 2 weeks later (Fig 1). The symptoms, medications, and acute complications between the 2 scans were recorded.

Statistics

Summary statistics are expressed as means and standard deviations (SDs). Data were analyzed using Wilcoxon ranked-pairs analysis for paired data, the Mann-Whitney U test for unpaired data with 2 groups, and the Kruskal-Wallis analysis of variance with more groups. The differences between proportions were tested with a χ² test and Fisher exact test. Correlation coefficients were calculated using Spearman rank correlation.

First MRI Examination

The subjects had had symptoms of an uncomplicated acute respiratory infection for an average of 6.5 days (range: 2–12 SD: 3.0), and the mean overall symptom score was 6.5 (SD: 4.0; Table 2). Typical examples of a normal MRI scan as well as scans with minor and major abnormal findings are presented in Fig 2. Altogether, 68% of the children had major abnormalities in their paranasal sinuses (Table 3). The opacity of these abnormal findings indicated in most cases the density of mucosal swelling. The mean MRI scores correlated significantly with the symptoms scores (r_s = 0.3, P = .02) but not with the duration of symptoms (r_s = −0.04, P = .73). Of the individual symptoms, nasal obstruction (P = .02), nasal discharge (P = .04), and fever (P = .02) were significantly related to the MRI scores.

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Fig 2.

A representative case of normal MRI finding (A), minor abnormality MRI finding (B), and major abnormality MRI finding (C) in a series of 60 children with acute respiratory infection. The increased blood flow in the inferior turbinate on the more congested right side after the nasal cycle is well seen in A as well as the mucosal edema in both maxillary sinuses and right ethmoidal sinus in B and major abnormal changes in ethmoidal and maxillary sinuses in C. The ostial region is not adequately visualized to allow estimation of ostial patency as a result of the sparse slices and that bony structures are not seen on MRI scans.

Follow-up MRI

Of the 26 children (12 boys and 14 girls) who attended the follow-up examination, 9 (35%) had fully recovered from the respiratory infection, 9 (35%) continued to have symptoms (mean [SD] symptom score 6.3 [3.9]), and 8 (30%) had developed a new respiratory infection (mean [SD] symptom score 3.5 [1.3]). Two children had received antimicrobial treatment (otitis media, thigh abscess).

Altogether, the MRI findings had improved significantly from the initial scans (P = .001; Table 4). Despite the improvement, however, 69% of these 26 most severely affected children still had major abnormalities in the sinuses (Table 4). The MRI scores at the control visit did not correlate significantly with the control visit’s symptom score (r_s = 0.21, P = .29) or the MRI scores at the initial visit (r_s = 0.09, P = .66).