Contrast-enhanced radiographic computed tomographic findings in patients with straight back syndrome.

Unlabelled: Straight back syndrome (SBS) is usually diagnosed by physical and chest radiographic findings. Radiographic computed tomographic (CT) findings are very useful for the diagnosis and the evaluation of its severity. The purpose is to evaluate the relationship between chest X-ray film and CT findings.

Subjects: We evaluated 26 patients (SBS group) and 11 normal subjects (control group). SBS group consisted of 15 patients without structural heart disease (group I) and 11 patients with other heart disease (group II).

Methods: (1) On the chest X-ray film, antero-posterior diameter (APD) of the thorax, transthoracic diameter (TTD), and APD/TTD ratio were measured. (2) On the CT image, three parameters were calculated; APD of the left atrium (LA diameter), APD/transverse diameter ratio of the heart (flattening ratio) and left side shift ratio of the heart (shifting ratio). (3) CT parameters were compared with APD/TTD ratio in patients and control group.

Results: (1) APD/TTD ratio was smaller in group I and II than control group (30.0 +/- 5.4, 30.5 +/- 4.0 v 44.6 +/- 2.7%, p < .001). (2) LA diameter was smaller in group I and II than control group (23.2 +/- 4.1, 26.0 +/- 8.6 v 30.0 +/- 6.5 mm, p < .01). Flattening ratio was also smaller in group I and II than control group (59.2 +/- 9.4, 61.8 +/- 8.6 v 75.4 +/- 13.2%, p < .01). Shifting ratio was greater in group I and II than control group (10.9 +/- 5.0, 11.9 +/- 4.5 v 8.4 +/- 4.0%, p < .01). (3) APD/TTD ratio correlated with LA diameter (r = .39, p < .05) and flattening ratio (r = .53, p < .001). APD/TTD ratio did not correlate with shifting ratio (r = -.27, NS).

Conclusions: APD/TTD ratio correlated with LA diameter and flattening ratio rather than shifting ratio. LA diameter and flattening ratio on the CT image were more useful for evaluating the severity.