Shoichiro Matsushita

MRI of Pulmonary Nodules

OBJECTIVE The purpose of this article is to review the current status of MRI for evaluation of pulmonary nodules. CONCLUSION Although clinical applications of pulmonary MRI face technical limitations, currently available MRI methods have contributed to morphologic and functional evaluations of pulmonary nodules.

Quantitative CT evaluation in patients with combined pulmonary fibrosis and emphysema: correlation with pulmonary function.

RATIONALE AND OBJECTIVES The purpose of this study was to evaluate the correlations between objective quantitative computed tomography (CT) measurements of the extent of emphysematous and fibrotic lesions and the results of pulmonary function tests (PFTs) in patients with combined pulmonary fibrosis and emphysema (CPFE). MATERIALS AND METHODS This study involved 43 CPFE patients who underwent CT and PFTs. The extent of emphysematous lesions was obtained by calculating the percentage of low attenuation area (%LAA) values lower than -950 Hounsfield units (HU). Fibrotic lesions were defined as high attenuation area (HAA) using thresholds with pixels between 0 and -700 HU, and the extent of fibrosis was obtained by calculating the percentage of HAA (%HAA). The correlations of %LAA and %HAA with PFTs were evaluated by the Spearman rank correlation coefficients and multiple linear regression analysis. RESULTS A significant negative correlation was found between %HAA and diffusing capacity of the lung for carbon monoxide (DLco) %predicted (ρ = -0.747; P < .001), whereas no significant correlation was found between %LAA and DLco %predicted. On multiple linear regression analysis, although the %HAA and %LAA were independent contributors to DLco %predicted, the predictive power of %HAA was superior to that of %LAA. CONCLUSIONS In CPFE, the extent of fibrosis has a more significant impact on DLco than emphysema.

Morphological disease progression of combined pulmonary fibrosis and emphysema: comparison with emphysema alone and pulmonary fibrosis alone.

Objectives The purpose of this study was to evaluate the differences in 5-year morphological changes among the patients with combined pulmonary fibrosis and emphysema (CPFE), emphysema alone, and fibrosis alone using quantitative computed tomography evaluation. Methods This study involved 42 patients with CPFE, 45 patients with emphysema alone, and 35 patients with fibrosis alone who underwent computed tomography scans twice (initial and 5 years after the initial scan). The extent of emphysematous lesions was obtained by calculating the percentage of low attenuation area (%LAA) lower than −950 Hounsfield units. Fibrotic lesion was defined as a high attenuation area (HAA) using thresholds with pixels between 0 and −700 Hounsfield units, and the extent of fibrosis was obtained by calculating the mean percentage of HAA (%HAA). For the quantitative evaluation of the total area of emphysematous change and fibrosis, the percentage of destructed lung area (%DA) was obtained by summing %LAA and %HAA. The 5-year changes of %LAA, %HAA, and %DA were calculated. Differences were evaluated by 1-way analysis of variance, which was followed by the Tukey-Kramer test. Results The mean change of %LAA was significantly higher in CPFE (7.4% ± 3.8%) than in emphysema alone (P < 0.05). The mean change of %DA was significantly higher in CPFE (12.9% ± 5.8%) than in emphysema alone (4.9% ± 2.8%) and fibrosis alone (7.1% ± 5.7%). Conclusions Morphological disease progression in CPFE differed from that in emphysema alone or fibrosis alone. In particular, the increase in emphysematous low-attenuation lesions was significantly higher in CPFE.

Relationship Between Quantitative CT of Pulmonary Small Vessels and Pulmonary Perfusion

OBJECTIVE The relationship between morphologic alterations of pulmonary small vessels and pulmonary perfusion has not been clarified. The purpose of this study was to evaluate the relationship between the cross-sectional area (CSA) of pulmonary small vessels alterations measured on CT images and pulmonary perfusion on lung perfusion scintigraphy. MATERIALS AND METHODS This study comprised 46 subjects who underwent both CT and lung perfusion scintigraphy. We measured CSA of pulmonary small vessels less than 5 mm(2) and 5-10 mm(2) using CT images and obtained the percentage of the right lung to whole lung in each CSA group (CSA<5,R/W and CSA5-10,R/W, respectively). Using (99m)Tc-macroaggregated albumin (MAA) lung perfusion scintigraphy, we obtained right and total lung counts and calculated the percentage of the right to whole-lung counts (MAAR/W). Those CT and scintigraphy measurements were also calculated separately each in right upper, right lower, left upper, and left lower zones. The correlations of CSA<5,R/W and CSA5-10,R/W with MAAR/W, the correlation between the percentage of each lung zone to whole-lung CSA<5 and the percentage of each corresponding lung zone to whole-lung MAA were evaluated. RESULTS The mean CSA<5,R/W was 58.1% ± 11.2%, and the mean MAAR/W was 59.3% ± 17.9%. CSA<5,R/W had a significant correlation with MAAR/W (ρ = 0.865, p < 0.0001), whereas significant correlation was found but was relatively weak between CSA5-10,R/W and MAAR/W (ρ = 0.512, p = 0.0003). The percentage of each lung zone to whole-lung CSA<5 had significant correlations with the percentage of each corresponding lung zone to whole-lung MAA. CONCLUSION Pulmonary small vessels alteration, as measured by CSA on CT images, significantly correlated with pulmonary perfusion.

Pulmonary arterial enlargement in patients with acute exacerbation of interstitial pneumonia.

The purpose of this study was to evaluate change in the size of the main pulmonary (PA) artery in patients with acute exacerbation of interstitial pneumonia (IP). Twenty-nine patients underwent computed tomography at baseline and at the time of acute IP exacerbation for the measurement of the diameters of the main PA and the ascending aorta. We found that the diameter of the main PA was significantly larger at the time of acute IP exacerbation than at baseline, which might reflect the alterations in pulmonary circulation.

Usefulness of Coronal Reconstruction CT Images for Quantitative Evaluation of the Cross-Sectional Area of Small Pulmonary Vessels

RATIONALE AND OBJECTIVES Cross-sectional area <5 mm(2) (CSA<5) is a computed tomography (CT) metric that has been used for the evaluation of pulmonary vessel alterations and perfusion. CSA<5 is calculated from three axial slices; thus, whether CSA<5 represents the small pulmonary vessel alterations in the whole lung remains unclear. The purpose of this study was to compare the measurements of CSA<5 using three axial slices and coronal reconstructed slices in the relationship between the measured CSA<5 and pulmonary perfusion measured using lung perfusion scintigraphy. MATERIALS AND METHODS This study comprised 28 subjects who underwent both noncontrast CT and lung perfusion scintigraphy. The present study measured CSA<5 using both three axial CT images and coronal reconstruction images and then obtained the percentage of the CSA in right lung to that in whole lung (R/W-CSA<5). Using anteroposterior and posteroanterior projections on technetium-99m macroaggregated albumin (MAA) lung perfusion scintigraphy, we obtained right and total lung counts and calculated the percentage of the right to whole lung counts (R/W-MAA). The correlations of the R/W-CSA<5 calculated using three axial slices (R/W-CSA(A)x<5) and coronal reconstructed slices (R/W-CSA(COR)<5) with R/W-MAA were evaluated using Spearman rank correlation analysis. RESULTS Both R/W-CSA(Ax)<5 and R/W-CSA(COR)<5 were significantly correlated with R/W-MAA; however, the correlation coefficient with R/W-CSA(COR)<5 (ρ = 0.842, P < .0001) was greater than that with R/W-CSA(Ax)<5 (ρ = 0.631, P = .0004). CONCLUSIONS Coronal reconstruction images appear suitable for quantitative measurement of CSA of small pulmonary vessels.

Changes in Cross-Sectional Area and Transverse Diameter of the Heart on Inspiratory and Expiratory Chest CT: Correlation with Changes in Lung Size and Influence on Cardiothoracic Ratio Measurement

Objective The aim of this study was to investigate physiological changes in cardiac area and diameters between inspiratory and expiratory chest computed tomography (CT), and to assess their correlation with lung size change and influence on cardiothoracic ratio (CTR) measurements. Materials and Methods The institutional review board of our institution approved this study, and informed consent was waived. Forty-three subjects underwent inspiratory and expiratory chest CT as part of routine clinical care. On both inspiratory and expiratory scans, lung volumes and maximum lung diameters (transverse and vertical directions) were measured. The maximum cardiac cross-sectional area (CSA) and the maximum transverse cardiac diameter were measured on both scans, and the CT-based CTR was calculated. Changes in the lung and cardiac measurements were expressed as the expiratory/inspiratory (E/I) ratios. Comparisons between inspiratory and expiratory measurements were made by the Wilcoxon signed-rank test. Correlations between the E/I ratios of lung and heart measurements were evaluated by Spearman’s rank correlation analysis. Results Cardiac CSA and transverse cardiac diameter was significantly larger on expiratory than on inspiratory CT (p < 0.0001). Significant negative correlations were found between the E/I ratios of these cardiac measurements and the E/I ratios of lung volume and vertical lung diameter (p < 0.01). CT-based CTR was significantly larger on expiration than on inspiration (p < 0.0001). Conclusions Heart size on chest CT depends on the phase of ventilation, and is correlated with changes in lung volume and craniocaudal lung diameter. The CTR is also significantly influenced by ventilation.

Quantitative computed tomography assessment of air trapping in relapsing polychondritis: correlations with spirometric values.

Objective The purpose of this study was to evaluate the relationship between quantitative computed tomography (CT) parameters of air trapping obtained with inspiratory and expiratory CT and pulmonary function tests (PFTs) in patients with relapsing polychondritis (RP). Materials and Methods This study included 23 patients with RP who underwent both CT and PFTs. In each patient, the mean lung density (MLD) was obtained by averaging CT attenuation of the lung parenchyma on both inspiratory and expiratory CT. The ratio of expiratory MLD to inspiratory MLD (E/I ratio) was also calculated. Correlations between those quantitative CT measurements and the results of PFTs were evaluated using Spearman rank correlation. Results The expiratory MLD and E/I ratio were significantly correlated with forced expiratory volume in 1 second (FEV1) %predicted, ratio of FEV1 to FVC (FEV1/FVC), and the mid expiratory phase of forced expiratory flow (FEF25%–75%) %predicted (expiratory MLD: FEV1 %predicted, r = 0.764, P < 0.0001; FEV1/FVC, r = 0.764, P < 0.0001; FEF25%–75% %predicted, r = 0.674, P < 0.001, respectively; the E/I ratio: FEV1 %predicted, r = −0.689, P < 0.001; FEV1/FVC, r = −0.689, P < 0.001; FEF25%–75% %predicted, r = −0.586, P < 0.01, respectively). The correlation between inspiratory MLD and PFTs did not reach statistical significance. Conclusions In RP patients, air trapping demonstrated on expiratory CT correlated with airway obstruction. This study may assist further refinement of the use of CT as quantitative evaluation for small and large airway obstruction in RP.

Selective venous sampling for primary hyperparathyroidism: how to perform an examination and interpret the results with reference to thyroid vein anatomy

Primary hyperparathyroidism (pHPT) causes hypercalcemia. The treatment for pHPT is surgical dissection of the hyperfunctioning parathyroid gland. Lower rates of hypocalcemia and recurrent laryngeal nerve injury imply that minimally invasive parathyroidectomy (MIP) is safer than bilateral neck resection. Current trends in MIP use can be inferred only by reference to preoperative localization studies. Noninvasive imaging studies (typically preoperative localization studies) show good detection rates of hyperfunctioning glands; however, there have also been cases of nonlocalization or discordant results. Selective venous sampling (SVS) is an invasive localization method for detecting elevated intact parathyroid hormone in the thyroid and/or internal jugular and brachiocephalic veins. SVS was developed mainly for postoperative patients with persistent or recurrent pHPT; however, SVS could also be useful before initial operations due to its high sensitivity to pHPT. Currently, SVS is generally indicated for recurrent HPT, and for cases with negative imaging study results for HPT or discordant results. Multi-detector row helical CT is useful for imaging the anatomy of the jugular and thyroid veins. Knowledge of the thyroid vein anatomy enables the creation of sampling points in the internal jugular and brachiocephalic veins for catheterization of the thyroid veins and venous anastomoses.

Longitudinal changes in structural abnormalities using MDCT in COPD: do the CT measurements of airway wall thickness and small pulmonary vessels change in parallel with emphysematous progression?

Background Recent advances in multidetector computed tomography (MDCT) facilitate acquiring important clinical information for managing patients with COPD. MDCT can detect the loss of lung tissue associated with emphysema as a low-attenuation area (LAA) and the thickness of airways as the wall area percentage (WA%). The percentage of small pulmonary vessels <5 mm2 (% cross-sectional area [CSA] <5) has been recently recognized as a parameter for expressing pulmonary perfusion. We aimed to analyze the longitudinal changes in structural abnormalities using these CT parameters and analyze the effect of exacerbation and smoking cessation on structural changes in COPD patients. Methods We performed pulmonary function tests (PFTs), an MDCT, and a COPD assessment test (CAT) in 58 patients with COPD at the time of their enrollment at the hospital and 2 years later. We analyzed the change in clinical parameters including CT indices and examined the effect of exacerbations and smoking cessation on the structural changes. Results The CAT score and forced expiratory volume in 1 second (FEV1) did not significantly change during the follow-up period. The parameters of emphysematous changes significantly increased. On the other hand, the WA% at the distal airways significantly decreased or tended to decrease, and the %CSA <5 slightly but significantly increased over the same period, especially in ex-smokers. The parameters of emphysematous change were greater in patients with exacerbations and continued to progress even after smoking cessation. In contrast, the WA% and %CSA <5 did not change in proportion to emphysema progression. Conclusion The WA% at the distal bronchi and the %CSA <5 did not change in parallel with parameters of LAA over the same period. We propose that airway disease and vascular remodeling may be reversible to some extent by smoking cessation and appropriate treatment. Optimal management may have a greater effect on pulmonary vascularity and airway disease than parenchymal deconstruction in the early stage of COPD.