Assessment of potential confounders when imaging pectus excavatum with chest radiography alone.

BACKGROUND: Chest radiography (CXR) has emerged as an attractive alternative imaging option for objective pre-operative assessment of pectus excavatum (PE) with comparable accuracy, reduced cost, and less radiation exposure when compared to computed tomography (CT). This study asked whether image quality, scoliosis, and asymmetry of the PE deformity would decrease the accuracy of CXR as compared to CT. METHODS: A database of PE patients receiving preoperative CXR and CT was created, and Haller-indices (HI) and correction-indices (CI) were calculated using each imaging modality. Each potential confounding variable were analyzed using Spearman correlations the Fisher r-to-z transformation test. RESULTS: The database was comprised of 77 patients. Image quality, scoliosis and the 'eccentric type' of asymmetry did not demonstrate any significant worsening of measurement accuracy. However, the correlation coefficients for CIs for those with and without the 'unbalanced type' of asymmetry were 0.593 and 0.890, respectively, with a Fisher r-to-z of 2.16 (p=.031). CONCLUSIONS: The accuracy of CXR-derived pectus indices remains quite favorable despite the heterogeneity from radiographic quality, scoliosis and chest wall asymmetry. Nonetheless, the unbalanced type of chest wall asymmetry did emerge as a significant confounder. As such, use of CXR alone in cases of gross chest wall asymmetry should be cautioned.

The case for using the correction index obtained from chest radiography for evaluation of pectus excavatum.

BACKGROUND: We previously reported the use of a computed tomography (CT)-based Correction Index (CI) as a more accurate assessment of pectus excavatum (PE) severity than the historically used Haller Index (HI). This study examines the diagnostic capabilities of the CI as assessed by lateral chest radiography (CXR). METHODS: A database of PE patients receiving preoperative CXR and CT was created. For each patient, a radiologist calculated a CT-based CI, while two pediatric surgeons independently calculated CXR CIs. RESULTS: The database was composed of 69 patients. Significant correlations were found between CXR CI estimates of the two observers and between the CXR and CT CI for each observer. Per our previous work, CT CIs were used in this study for identifying patients meeting surgical criteria (CT CI≥28%). Observed CXR CIs demonstrated good interrater reliability. The sensitivity (0.83) and specificity (0.77) of CXR in diagnosing severe PE (CT CI≥28%) was high. However, sensitivity (0.89) markedly improved when only considering measured CXR CIs≤26%, and combined specificity rose to 0.86 when only considering measured CXR CIs≥30%. CONCLUSIONS: We recommend the CI as measured by lateral CXR for the preoperative evaluation of PE, with CT used as a confirmatory test in patients measured to have a CXR CI between 26% and 30%.

The correction index: setting the standard for recommending operative repair of pectus excavatum.

BACKGROUND: The Haller index, derived from a chest computed tomography scan, remains the standard for determining candidacy for pectus excavatum repair (Haller index≥3.25). However, it has been suggested that this index may not accurately reflect pectus severity in patients with abnormal chest wall morphologies. This study explores a new, more appropriate criteria for recommending repair based on a correction index, while still incorporating the standard set by the Haller index. METHODS: A database of 75 patients with pectus excavatum who received computed tomography scans was compiled. For each patient, a staff radiologist calculated the Haller index, a correction index, and an ideal chest index from the computed tomography image with the greatest sternal depression. A correlation was assessed between all Haller and correction indices and separately for those with standard and nonstandard chest dimensions as assessed by an ideal chest index. RESULTS: There was a modest correlation between the Haller and correction indices measured in this cohort (r=0.79; p<0.0001). When patients with aberrant ideal chest dimensions were removed from analysis, Haller and correction indices showed a stronger correlation (r=0.86; p<0.0001). CONCLUSIONS: The correction index provides an accurate assessment of pectus severity, and by the nature of the measurement, reflects the potential degree of operative repair. The Haller index correlates well with the correction index in pectus patients with standard chest wall dimensions, but is quite discrepant in the nonstandard chest. We recommend operative repair for pectus excavatum with a correction index of 28% or more, because this value correlates with the long-accepted standard (Haller index≥3.25) and this index remains accurate even in nonstandard chest morphologies.

Defining the role of chest radiography in determining candidacy for pectus excavatum repair.

OBJECTIVE: The Haller index (HI), derived from computed tomography (CT) of the chest, remains the standard for determining pectus excavatum (PE) severity. The ability to accurately determine PE severity from chest radiography (CXR) may provide substantial benefits. This study proposes to establish data-driven criteria for the use of CXR as a diagnostic modality in the preoperative evaluation of patients with PE. METHODS: A database of 77 patients with PE receiving preoperative CXR and CT was created. Haller indices were obtained from CT scans. Two cardiothoracic surgeons, blinded to the CT HI scores, independently calculated CXR HIs. Interrater reliability, correlations, sensitivity, specificity, and accuracy were calculated. RESULTS: A significant correlation was found between CXR HI estimates of the two observers, r = 0.84. Computed tomography HIs were used as the standard for identifying patients meeting surgical criteria (CT HI ≥3.2). From this, sensitivities, specificities, and accuracies were calculated for the corresponding CXR HIs determined by each observer. Observer CXR HI estimates had a sensitivity of 0.94 and 0.92, specificity of 0.77 and 0.42, and accuracy of 0.88 and 0.75. CONCLUSIONS: We found a strong correlation between HIs calculated with each modality. In addition, CXR HIs demonstrated good interrater reliability. Although the sensitivity of CXR in diagnosing severe PE (CT HI ≥3.2) was high, specificity was less convincing. However, when using a cutoff of CXR HIs of 3.75 or greater, combined specificity was quite high (0.96). We recommend replacing CT with CXR in the preoperative evaluation for PE. Computed tomography should be used as a confirmatory test for CXR HIs between 3.2 and 3.75.

Norwood reconstruction using continuous coronary perfusion: a safe and translatable technique.

BACKGROUND: Continuous coronary perfusion during Norwood reconstruction offers the theoretic advantage of less postoperative cardiac dysfunction. The avoidance of a cardiac and circulatory arrest period allows time for a more deliberate aortic reconstruction while the heart remains beating. This single-center study was designed to compare patient results using this method vs standard cardiac arrest for Norwood reconstruction. METHODS: A retrospective review was done of 32 patients undergoing Norwood reconstruction from November 2004 to July 2011. The operations in the most recent 16 consecutive patients were performed under deep hypothermia with constant coronary and cerebral perfusion. Continuous coronary perfusion was provided by a cannula inserted into the proximal aorta. The operations in the prior 16 consecutive patients were performed using deep hypothermia, selective cerebral perfusion, and cardioplegic arrest during aortic reconstruction. RESULTS: Survival in the beating-heart group was 87.5% (14 of 16) vs 62.5% (10 of 16) in the standard group (p = 0.22). No patients in the beating-heart group required extracorporeal membrane oxygenation vs 3 in the standard group. Postoperative cardiac function was similar for both groups. The beating-heart cohort had lower peak lactate levels (8.2 mEq/L) than the standard group (10.7 mEq/L, p = 0.022). CONCLUSIONS: This study presents the largest series of Norwood operations in which the entire aorta is augmented while delivering continuous coronary perfusion. The technique is applicable to any size aorta and represents a safe alternative because outcomes for survival, freedom from extracorporeal membrane oxygenation, postoperative cardiac function, and lactate levels were all noninferior compared with the standard technique.