Jun Arisawa

Assessment of the intrapulmonary ventilation-perfusion distribution after the Fontan procedure for complex cardiac anomalies: Relation to pulmonary hemodynamics

In 12 patients who underwent the Fontan procedure for complex cardiac anomalies, lung scanning with xenon-133 was performed to assess the intrapulmonary ventilation-perfusion distribution, and comparison was made with a control group. All data were then analyzed in relation to either pre- or postoperative pulmonary hemodynamic data. In ventilation scans, the intrapulmonary distribution in the right lung was almost normal. In perfusion scans, an abnormal increased upper to lower lobe perfusion ratio greater than the normal value found in the control group was noted in seven patients (58.3%). There was a significant correlation (p less than 0.02) between the upper to lower lobe perfusion ratio and postoperative pulmonary vascular resistance. Furthermore, this perfusion ratio correlated inversely with the preoperative (p less than 0.005) and postoperative (p less than 0.02) right pulmonary artery area index, defined as the ratio of cross-sectional area to the normal value. Of five patients with less than 90% arterial oxygen saturation, four showed an abnormal distribution of pulmonary blood flow greater than the normal perfusion ratio. No patient had evidence of a pulmonary arteriovenous fistula by the echocardiographic contrast study. These results suggest that abnormal distribution of pulmonary blood flow to the upper lung segment may develop in patients after the Fontan procedure, and that insufficient size of the pulmonary artery before operation and the consequent postoperative elevation of pulmonary vascular resistance may be responsible for this perfusion abnormality.

Assessment of ventricular contractile state and function in patients with univentricular heart

To elucidate the ventricular contractile state and function in patients with univentricular heart, the ventricular volume, mass, ejection phase index, and wall stress were evaluated with biplane ventriculography and pressure measurement in 41 patients: 18 with left ventricular (LV) type (age, 6.4 +/- 6.1 years) and 23 with right ventricular (RV) type (age, 5.7 +/- 4.1 years), and data from patients with univentricular heart were compared with data from 19 normal control subjects (age, 7.2 +/- 4.3 years). Although the end-diastolic and end-systolic volumes were significantly greater in both types of univentricular heart than in the normal control group, the volumes for the LV and RV type patients did not differ from each other. The ejection fraction (EF) was depressed in both patient types of univentricular heart and was significantly (p less than 0.005) lower in the RV type than in the LV type patients (0.56 +/- 0.05 for LV type, 0.50 +/- 0.07 for RV type, and 0.64 +/- 0.03 for the control group). The ventricular mass was larger in both patient types of univentricular heart than in that of the control group, whereas the ratio of ventricular mass to end-diastolic volume was significantly (p less than 0.001) lower in the RV type patients than in the LV type patients and the control group (0.79 +/- 0.18 g/ml for LV type, 0.51 +/- 0.10 for RV type, and 0.82 +/- 0.13 for control group). End-systolic stress was significantly elevated in both types of univentricular heart (241 +/- 45 for LV type, 328 +/- 52 for RV type, and 205 +/- 26 kdynes/cm2 for the control group) and significantly (p less than 0.001) greater in the RV type than in the LV type patients. There was a significant inverse correlation (p less than 0.001) between end-systolic stress and the ratio of mass to end-diastolic volume in all the patients. In 27 patients (12 patients for LV type, 15 for RV type) the mean normalized systolic ejection rate corrected for heart rate (MNSERc) clearly fell below the 95% confidence limit of the normal end-systolic stress-MNSERc relation. The end-systolic stress:end-systolic volume ratio was also significantly depressed in both patient types of univentricular heart (3.49 +/- 1.77 for LV type, 4.07 +/- 2.13 for RV type, and 7.20 +/- 1.32 for the control group). In these variables, however, there were no significant differences between LV and RV type patients of univentricular heart.(ABSTRACT TRUNCATED AT 400 WORDS)

Quantitative cineangiographic analysis of ventricular volume and mass in patients with single ventricle: relation to ventricular morphologies.

With the use of biplane selective ventriculography, the ventricular volume, ejection fraction, and ventricular mass were evaluated in 28 patients with a single ventricle, and those with the left ventricular type (LV type, 12 patients) and right ventricular type (RV type, 16 patients) were compared. There were no significant differences in terms of age, hemoglobin, systemic oxygen saturation, or pulmonary-to-systemic flow ratio in the two groups. No patients with atrioventricular valve regurgitation were included. The ventricular cavity volume was calculated by the area-length method. The ventricular mass volume was determined as the shell volume created by subtracting the ventricular cavity volume from the total ventricular volume calculated by adding the free wall thickness to the chamber dimensions. The ventricular mass volume was converted to mass by multiplying by the gravity of the heart muscle. There was no significant difference between patients with the LV type and RV type of single ventricle with respect to the end-diastolic ventricular volume (188 +/- 53 and 179 +/- 61 ml/m2 in LV and RV types, respectively), end-systolic volume (88 +/- 31 and 84 +/- 27 ml/m2), or ejection fraction (0.54 +/- 0.06 and 0.52 +/- 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

High-resolution CT and pulmonary function tests in collagen vascular disease: comparison with idiopathic pulmonary fibrosis.

To estimate whether the lung abnormalities seen in collagen vascular diseases (CVD) were similar or distinct to those seen in idiopathic pulmonary fibrosis (IPF), and to ascertain whether the extent of the abnormalities on high-resolution CT (HRCT) correlated with pulmonary function, we reviewed HRCT findings and pulmonary function test results of 64 patients with either CVD (n = 55) or IPF (n = 9). Response to corticosteroid treatment was also evaluated in 20 of the 64. High incidence of honeycomb lesion was observed in IPF (9/9, 100%) and in progressive systemic sclerosis (PSS) (11/14, 79%). CVD, except for PSS, had a low incidence of honeycomb lesion (27%). On the other hand, incidence of ground-glass shadow in CVD (47/55, 85%) was the same as that in IPF (8/9, 89%). Diffusing capacity significantly correlated with the extent of all parenchymal abnormalities in all CVD and IPF, with honeycomb lesion in PSS, and with ground-glass shadow or air-space consolidation in CVD except for PSS (r < -0.7, P < 0.001). In all 15 cases in which corticosteroid therapy was effective, no honeycomb lesions were seen. Collagen vascular disease, except for PSS, had a different pattern of disease than IPF. The morphologic changes seen on HRCT correlated well with pulmonary function in CVD.

Fractal analysis for classification of ground-glass opacity on high-resolution CT: an in vitro study.

PURPOSE Fractal analysis based on the fractional Brownian motion model was applied ground-glass opacity on high-resolution CT (HRCT) to investigate its usefulness in distinguishing ground-glass opacity caused by nonfibrotic disease processes and that caused by fibrotic disease processes, confirming pathology. METHOD Twenty-one postmortem lungs inflated and fixed by Heitzmans method were evaluated. By correlating HRCT and pathology, the lungs were classified into nonfibrotic disease processes and fibrotic disease processes. Fractal analysis based on the fractional Brownian motion model provides the parameter H, which is a statistical measure related to the psychophysical perception of roughness. For regions of interest positioned over ground-glass opacities on HRCT, conventional statistics (mean value and SD) and the estimated H values were calculated using a workstation. RESULTS Pathologically, 10 lung specimens were categorized as nonfibrotic disease processes and 11 as fibrotic disease processes. Whereas the conventional statistics had considerable overlap in two disease processes, the overlapping was drastically reduced in the H values. The H values of fibrotic disease processes (mean +/- SD, 0.423 +/- 0.064) were significantly greater than those of nonfibrotic disease processes (0.297 +/- 0.036) (p < 0.001). CONCLUSION Fractal analysis based on the fractional Brownian motion model may provide a new promising scheme for assessing ground-glass opacity on HRCT caused by either nonfibrotic or fibrotic disease processes.

Left ventricular regional systolic motion in patients with right ventricular pressure overload

Left ventricular regional systolic motion was investigated in patients with right ventricular pressure overload and 10 controls using tagged cine magnetic resonance imaging. The regional shortening fraction was determined in four segments (septal, lateral, inferior, and anterior) on the short-axis image. An asynchrony index, nonhomogeneity of regional shortening, was calculated. Septal shortening in these patients was depressed, and showed an inverse correlation with the right-to-left ventricular peak pressure ratio (r=-0.80, P<0.01). Lateral shortening was greater in the patients than in the controls (P<0.01). The asynchrony index was significantly greater in the patients than in the controls (P<0.01), and correlated with the right-to-left systolic pressure ratio (r=0.64, P=0.02) and the left ventricular end-diastolic pressure (r=0.79, P<0.01). The altered distribution of regional circumferential shortening results in an increased heterogeneity of regional systolic motion. These findings may have important implications for the assessment of ventricular function in patients with right ventricular pressure overload.

Normal Nonuniformity of Left Ventricular Contraction: Assessment by Cine MR Imaging with Presaturation Myocardial Tagging

Purpose: To identify the normal performance of left ventricular (LV) regional contraction using cine MR imaging with presaturation myocardial tagging. Material and Methods: Sixteen normal volunteers were examined on a 1.5 T MR system with tagging cine sequences. Tags were applied at end-diastole as 2 parallel black lines on short-axis and 4-chamber sections, and the fractional shortenings were calculated at 7 LV locations. Results: The following results were obtained with significance: a transmural gradient of contractility in the short-axis section; prolonged late-systolic endocardial shortening and epicardial early termination in the free wall; initial delay of shortening in the anterior wall; apical predominance of contractility; predominance of circumferential shortening in the free wall and of meridional shortening in the septum. These findings could be associated with myocardial fiber architecture, presumed wall stress and temporal asynergy of excitation. Conclusion: Cine MR imaging with myocardial tagging proved to be useful in assessing the nonuniformity of LV contraction.

Mechanism of gravity-dependent atelectasis. Analysis by nonradioactive xenon-enhanced dynamic computed tomography.

Tomiyama N, Takeuchi N, Imanaka H, Matsuura N, Morimoto S, Ikczoe J, Johkoh T, Arisawa J, Kozuka T. Mechanism of gravity-dependent atelectasis: analysis by nonradioactive xenon-enhanced dynamic computed tomography. Invest Radiol 1993;28:633-638. RATIONALE AND OBJECTIVES.The physiologic mechanism of gravity-dependent atelectasis (GDA), a common finding identified during anesthesia, is not well understood. The purpose of this study was to determine whether an inherent reduction in alveolar volume or a reduction in alveolar ventilation is the more important causative factor for the development of GDA in an experimental animal model. METHODS.After uniform reduction of lung volume in ten rabbits by artificially induced pneumoperitoneum, dynamic inhalation computed tomography (CT) was performed using 50% nonradioactive xenon in oxygen. Time-CT attenuation value curves were fitted to an exponential function, CT value=a - b X e-kt, and K value, which is proportional to the alveolar ventilation/alveolar volume ratio, was calculated by regression analysis. RESULTS.Gravity-dependent atelectasis occurred only in 5 of 10 rabbits. In this group, K values in the dorsal regions increased before the appearance of GDA. No significant change in K values in the ventral regions was observed. CONCLUSION.One mechanism of GDA may be a preferential reduction in alveolar volume without small airway collapse rather than alveolar volume loss secondary to decreased ventilation.

Gravity-dependent Atelectasis: Radiologic, Physiologic and Pathologic Correlation in Rabbits on High-frequency Oscillation Ventilation

The authors identify the radiologic features of progressive atelectasis induced under conditions of reduced lung volume. Control (n = 5) and experimental (n = 7) animals were placed on high-frequency oscillation (HFO) ventilation (mean airway pressure: 3 cm H2O) for 6 hours. In the experimental animals, lung volume was artificially reduced by pneumoperitoneum during HFO ventilation. Computed tomography scans and chest radiographs were obtained every hour, and arterial blood gases analyzed. No changes were detected in the control animals. In the experimental animals, in which hypoxemia developed, homogeneous opacity in the dependent lung was found on CT images, and chest radiographs showed a diffuse homogenous shadow with loss of lung volume. Study of pathologic sections from the lung showed that the roentgenographic findings represented atelectasis. The lung was divided into three zones, from dependent to nondependent regions: severe atelectasis, mild atelectasis, and normal lung. Hyperinflations eliminated atelectasis seen on the CT images and alleviated hypoxemia; however an undesirable effect that causes barotrauma also was observed.

Interpretation of Subtle Interstitial Chest Abnormalities: Conventional Radiography Versus High-Resolution Storage-Phosphor Radiography~A Preliminary Study

To evaluate the reliability of digital chest radiography in diagnosing subtle interstitial lung abnormalities, we performed several clinical studies including a comparison of conventional screen-film radiography and storage-phosphor radiography (2 K × 2 K pixels, 10 bit), and a comparison of conventional screen-film radiography and film-digitized radiography (2 K × 2 K pixels, 10 bit). From these previous studies, a spatial resolution of 0.2-mm pixel size was considered inadequate to diagnose subtle interstitial lung diseases. Under these circumstances, the newly developed Fuji Computed Radiography system (FCR 9000; Fuji Photo Film, Tokyo, Japan) has recently become available. This system provides 0.1-mm pixel size (4 K × 5 K pixels, 10-bit depth) and life-size hard copies (14×17 inches). To evaluate the reliability of new high-resolution storagephosphor radiography (FCR 9000) in diagnosing simulated subtle interstitial abnormalities (including simulated lines, micronodules, and groundglass opacities), the differences among radiologists in interpreting conventional screen-film radiographs and life-size high-resolution storage-phosphor radiographs were studied. Observation was made by eight experienced chest radiologists, and receiver-operating characteristic (ROC) analysis was performed. There was no significant difference in detecting in subtle simulated interstitial abnormalities between conventional film-screen radiography and high-resolution storage-phosphor radiography. For all three types of abnormalities, there was no significant difference between conventional and storage-phosphor radiography. In conclusion, the high-resolution storage-phosphor chest radiography (0.1-mm pixel size, 10-bit depth) may be substituted for conventional chest radiography in the detection of subtle interstitial abnormalities.