Morphological measurements in computed tomography correlate with airflow obstruction in chronic obstructive pulmonary disease: systematic review and meta-analysis

Objectives

To determine the correlation between CT measurements of emphysema or peripheral airways and airflow obstruction in chronic obstructive pulmonary disease (COPD).

Methods

PubMed, Embase and Web of Knowledge were searched from 1976 to 2011. Two reviewers independently screened 1,763 citations to identify articles that correlated CT measurements to airflow obstruction parameters of the pulmonary function test in COPD patients, rated study quality and extracted information. Three CT measurements were accessed: lung attenuation area percentage?1 %pred) and FEV₁ divided by the forced volume vital capacity.

Results

Seventy-nine articles (9,559 participants) were included in the systematic review, demonstrating different methodologies, measurements and CT airflow obstruction correlations. There were 15 high-quality articles (2,095 participants) in the meta-analysis. The absolute pooled correlation coefficients ranged from 0.48 (95?% CI, 0.40 to 0.54) to 0.65 (0.58 to 0.71) for inspiratory CT and 0.64 (0.53 to 0.72) to 0.73 (0.63 to 0.80) for expiratory CT.

Conclusions

CT measurements of emphysema or peripheral airways are significantly related to airflow obstruction in COPD patients. CT provides a morphological method to investigate airway obstruction in COPD.

Key Points

? Computed tomography is widely performed in patients with chronic obstructive pulmonary disease (COPD) ? CT provides quantitative morphological methods to investigate airflow obstruction in COPD ? CT measurements correlate significantly with the degree of airflow obstruction in COPD ? Expiratory CT measurements correlate more strongly with airflow obstruction than inspiratory CT ? Low-dose CT decreases the radiation dose for diagnosis and quantitative emphysema evaluation     

Magnetic resonance imaging to assess the effect of exercise training on pulmonary perfusion and blood flow in patients with pulmonary hypertension

Objectives

To evaluate whether careful exercise training improves pulmonary perfusion and blood flow in patients with pulmonary hypertension (PH), as assessed by magnetic resonance imaging (MR).

Methods

Twenty patients with pulmonary arterial hypertension or inoperable chronic thromboembolic PH on stable medication were randomly assigned to control (n?=?10) or training groups (n?=?10). Training group patients received in-hospital exercise training; patients of the sedentary control group received conventional rehabilitation. Medication remained unchanged during the study period. Changes of 6-min walking distance (6MWD), MR pulmonary flow (peak velocity) and MR perfusion (pulmonary blood volume) were assessed from baseline to week 3.

Results

After 3 weeks of training, increases in mean 6MWD (P?=?0.004) and mean MR flow peak velocity (P?=?0.012) were significantly greater in the training group. Training group patients had significantly improved 6MWD (P?=?0.008), MR flow (peak velocity ?9.7?±?8.6 cm/s, P?=?0.007) and MR perfusion (pulmonary blood volume +2.2?±?2.7 mL/100 mL, P?=?0.017), whereas the control group showed no significant changes.

Conclusion

The study indicates that respiratory and physical exercise may improve pulmonary perfusion in patients with PH. Measurement of MR parameters of pulmonary perfusion might be an interesting new method to assess therapy effects in PH. The results of this initial study should be confirmed in a larger study group.

Key Points

? Quantification of magnetic resonance perfusion is feasible in patients with pulmonary hypertension. ? Quantified magnetic resonance perfusion may become useful for non-invasive monitoring of treatment. ? Quantification of lung perfusion allows new insights into lung (patho-)physiology of PH. ? Careful exercise training improves pulmonary perfusion and blood flow in patients with PH.     

Differentiation of malignant and benign pulmonary nodules with first-pass dual-input perfusion CT

Objective

To assess diagnostic performance of dual-input CT perfusion for distinguishing malignant from benign solitary pulmonary nodules (SPNs).

Methods

Fifty-six consecutive subjects with SPNs underwent contrast-enhanced 320-row multidetector dynamic volume CT. The dual-input maximum slope CT perfusion analysis was employed to calculate the pulmonary flow (PF), bronchial flow (BF), and perfusion index $ \left( {\mathrm{PI},={{\mathrm{PF}} \left/ {{\left( {\mathrm{PF} + \mathrm{BF}} \right)}} \right.}} \right) $ . Differences in perfusion parameters between malignant and benign tumours were assessed with histopathological diagnosis as the gold standard. Diagnostic value of the perfusion parameters was calculated using the receiver-operating characteristic (ROC) curve analysis.

Results

Amongst 56 SPNs, statistically significant differences in all three perfusion parameters were revealed between malignant and benign tumours. The PI demonstrated the biggest difference between malignancy and benignancy: 0.30?±?0.07 vs. 0.51?±?0.13 , P?<?0.001. The area under the PI ROC curve was 0.92, the largest of the three perfusion parameters, producing a sensitivity of 0.95, specificity of 0.83, positive likelihood ratio (+LR) of 5.59, and negative likelihood ratio (?LR) of 0.06 in identifying malignancy.

Conclusions

The PI derived from the dual-input maximum slope CT perfusion analysis is a valuable biomarker for identifying malignancy in SPNs. PI may be potentially useful for lung cancer treatment planning and forecasting the therapeutic effect of radiotherapy treatment.

Key Points

? Modern CT equipment offers assessment of vascular parameters of solitary pulmonary nodules (SPNs) ? Dual vascular supply was investigated to differentiate malignant from benign SPNs. ? Different dual vascular supply patterns were found in malignant and benign SPNs. ? The perfusion index is a useful biomarker for differentiate malignancy from benignancy.     

Quantitative evaluation of MR perfusion imaging using blood pool contrast agent in subjects without pulmonary diseases and in patients with pulmonary embolism

Objective

To assess the feasibility of time-resolved parallel three-dimensional magnetic resonance imaging (MRI) for quantitative analysis of pulmonary perfusion using a blood pool contrast agent.

Methods

Quantitative perfusion analysis was performed using novel software to assess pulmonary blood flow (PBF), pulmonary blood volume (PBV) and mean transit time (MTT) in a quantitative manner.

Results

The evaluation of lung perfusion in the normal subjects showed an increase of PBF, PBV ventrally to dorsally (gravitational direction), and the highest values at the upper lobe, with a decrease to the middle and lower lobe (isogravitational direction). MTT showed no relevant changes in either the gravitational or isogravitational directions. In comparison with normally perfused lung areas (in diseased patients), the pulmonary embolism (PE) regions showed a significantly lower mean PBF (20?±?0.6?ml/100?ml/min, normal region 94?±?1?ml/100?ml/min; P?P?P?Conclusion Our results demonstrate the feasibility of using time-resolved dynamic contrast-enhanced MRI to determine normal range and regional variation of pulmonary perfusion and perfusion deficits in patients with PE.

Key Points

? Recently introduced blood pool contrast agents improve MR evaluation of lung perfusion ? Regional differences in lung perfusion indicating a gravitational and isogravitational dependency. ? Focal areas of significantly decreased perfusion are detectable in pulmonary embolism.     

Clinical application of dual-source CT in the evaluation of patients with lung cancer: correlation with perfusion scintigraphy and pulmonary function tests

Purpose

This study was done to assess the diagnostic potential of dual-source computed tomography (DSCT) in the functional evaluation of lung cancer patients undergoing surgical resection. The CT data were compared with pulmonary perfusion scintigraphy and pulmonary function tests (PFTs).

Materials and methods

All patients were evaluated with DSCT, scintigraphy and PFTs. The DSCT scan protocol was as follows: two tubes (80 and 140 kV; Care Dose protocol); 70 cc of contrast material (5 cc/s); 5- to 6-s scan time; 0.6 mm collimation. After the automatic calculation of lung perfusion with DSCT and quantification of air volumes and emphysema with dedicated software applications, the perfusional CT studies were compared with scintigraphy using a visual score for perfusion defects; CT air volumes and emphysema were compared with PFTs.

Results

The values of accuracy, sensitivity, specificity and positive (PPV) and negative (NPV) predictive values of DSCT compared with perfusion scintigraphy as the reference standard were: 0.88, 0.84, 0.90, 0.93 and 0.88, respectively. The McNemar test did not identify significant differences either between the two imaging techniques (p=0.07) or between CT and PFTs (p=0.09).

Conclusions

DSCT is a robust and promising technique that provides important and accurate information on lung function.     

Comparison of image quality and radiation dose of different pulmonary CTA protocols on a 128-slice CT: high-pitch dual source CT, dual energy CT and conventional spiral CT

Objectives

To compare image quality and radiation dose of high-pitch dual-source computed tomography (DSCT), dual energy CT (DECT) and conventional single-source spiral CT (SCT) for pulmonary CT angiography (CTA) on a 128-slice CT system.

Methods

Pulmonary CTA was performed with five protocols: high-pitch DSCT (100?kV), high-pitch DSCT (120?kV), DECT (100/140?kV), SCT (100?kV), and SCT (120?kV). For each protocol, 30 sex, age, and body-mass-index (mean 25.3?kg/m²) matched patients were identified. Retrospectively, two observers subjectively assessed image quality, measured CT attenuation (HU±SD) at seven central and peripheral levels, and calculated signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR). Radiation exposure parameters (CTDIvol and DLP) were compared.

Results

Subjective image quality was rated good to excellent in >92% (>138/150) with an interobserver agreement of 91.4%. The five protocols did not significantly differ in image quality, neither by subjective, nor by objective measures (SNR, CNR). By contrast, radiation exposure differed between protocols: significant lower radiation was achieved by using high-pitch DSCT at 100?kV (p?Conclusions SCT, high-pitch DSCT, and DECT protocols techniques result in similar subjective and objective image quality, but radiation exposure was significantly lower with high-pitch DSCT at 100?kV.

Key Points

• New CT protocols show promising results in pulmonary embolism assessment.
• High-pitch dual-source CT (DSCT) at 100?kV provides radiation dose savings for pulmonary CTA.
• High-pitch DSCT at 100?kV maintains diagnostic image quality for pulmonary CTA.
• Dual energy CT uses more radiation but also provides lung perfusion evaluation.
• Whether the additional perfusion data is worth the extra radiation remains undetermined.

     

The effect of iterative reconstruction on computed tomography assessment of emphysema, air trapping and airway dimensions

Objectives

To determine the influence of iterative reconstruction (IR) on quantitative computed tomography (CT) measurements of emphysema, air trapping, and airway wall and lumen dimensions, compared to filtered back-projection (FBP).

Methods

Inspiratory and expiratory chest CTs of 75 patients (37 male, 38 female; mean age 64.0?±?5.7?years) were reconstructed using FBP and IR. CT emphysema, CT air trapping and airway dimensions of a segmental bronchus were quantified using several commonly used quantification methods. The two algorithms were compared using the concordance correlation coefficient (p _c) and Wilcoxon signed rank test.

Results

Only the E/I-ratio_MLD as a measure of CT air trapping and airway dimensions showed no significant differences between the algorithms, whereas all CT emphysema and the other CT air trapping measures were significantly different at IR when compared to FBP (P?Conclusion The evaluated IR algorithm significantly influences quantitative CT measures in the assessment of emphysema and air trapping. However, the E/I-ratio_MLD as a measure of CT air trapping, as well as the airway measurements, is unaffected by this reconstruction method. Quantitative CT of the lungs should be performed with careful attention to the CT protocol, especially when iterative reconstruction is introduced.

Key Points

? New techniques in CT allow numerous quantitative measurements of lung function. ? Iterative reconstruction influences quantitative CT measurements of emphysema and air trapping. ? Expiratory-to-inspiratory ratio of mean lung density and airway measurements are unaffected by iterative reconstruction. ? Quantitative lung-CT should be performed with careful attention to the CT protocol.     

Chronic obstructive pulmonary disease (COPD) patients with osteoporotic vertebral compression fractures (OVCFs): improvement of pulmonary function after percutaneous vertebroplasty (VTP)

Objectives

To investigate the changes of respiratory function in patients affected by chronic obstructive pulmonary disease (COPD) with single dorsal osteoporotic vertebral compression fractures (OVCFs) treated with vertebroplasty (VTP).

Methods

Forty-five patients affected by COPD and single dorsal OVCF underwent VTP (29 men, 16 women; mean age 71.4 years, range 65–77 years). Inclusion criteria were magnetic resonance findings of bone marrow oedema, without intracanal bone fragments and refractory pain to medical treatment for at least 3 months. Osteoporosis was assessed by bone densitometry. Spirometry was performed before and after treatment.

Results

A significant VAS-score decrease was observed 1 week after VTP, with a subsequent decrease over time; vital capacity (VC) and forced vital capacity (FVC) improved over time, reaching a plateau at 3 months. Forced expiratory volume at 1 s (FEV₁) did not significantly differ between the pre-VTP values and follow-up values. A significant correlation was observed between VAS-score values and VC, and VAS-score values and FVC. No significant correlation was observed between VAS-score values and FEV₁ values.

Conclusions

VTP improves restrictive ventilatory impairment in patients with moderate and severe COPD affected by single thoracic OVCFs. We recommend this treatment in the management of these patients.

Key Points

? Osteoporosis is a major comorbidity in chronic obstructive pulmonary disease (COPD) patients. ? Pain due to osteoporotic vertebral compression fractures worsens respiratory failure in COPD. ? Vertebroplasty improves ventilatory impairment in COPD patients with osteoporotic vertebral compression fractures.     

How much do GOLD stages reflect CT abnormalities in COPD patients?

Purpose

Severity of chronic obstructive pulmonary disease (COPD) can be graded using the classification released in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) report. Such classification is essentially based on spirometry and does not recognise the role of other measures. The aim of this study was to assess whether the GOLD stages correlate with the extent of pulmonary emphysema and other ancillary computed tomography CT features in a population of smokers with stable COPD.

Materials and methods

Based on clinical assessment and lung-function testing, patients were classified according to the GOLD criteria. CT scans were visually evaluated for extent of emphysema and airway abnormalities.

Results

A total of 43 patients were enrolled. The amount of emphysema was described as minimal in six patients with stage 0, and as moderate in seven patients with stage 0. In stages I and II, the extent of emphysema ranged from minimal to severe, whereas we observed the presence of severe emphysema in most patients in stages III and IV. According to the regression model, only CT emphysema extent independently predicted the GOLD stage (r ²=0.58; p<0.001). The cutoff value of emphysema extent of 31.5% allowed us to distinguish patients with a GOLD stage ≥III.

Conclusions

Although we found a significant correlation between CT emphysema extent and GOLD stages, different percentage of emphysema extent can be observed among each GOLD stage. The upper limit of 31.5% of emphysema extent may indicate a boundary for a clinically worsening status.     

Assessment of regional emphysema,air-trapping and Xenon-ventilation using dual-energy computed tomography in chronic obstructive pulmonary disease patients

Objectives

To compare the parenchymal attenuation change between inspiration/expiration CTs with dynamic ventilation change between xenon wash-in (WI) inspiration and wash-out (WO) expiration CTs.

Methods

52 prospectively enrolled COPD patients underwent xenon ventilation dual-energy CT during WI and WO periods and pulmonary function tests (PFTs). The parenchymal attenuation parameters (emphysema index (EI), gas-trapping index (GTI) and air-trapping index (ATI)) and xenon ventilation parameters (xenon in WI (Xe-WI), xenon in WO (Xe-WO) and xenon dynamic (Xe-Dyna)) of whole lung and three divided areas (emphysema, hyperinflation and normal) were calculated on virtual non-contrast images and ventilation images. Pearson correlation, linear regression analysis and one-way ANOVA were performed.

Results

EI, GTI and ATI showed a significant correlation with Xe-WI, Xe-WO and Xe-Dyna (EI R?=??.744, ?.562, ?.737; GTI R?=??.621, ?.442, ?.629; ATI R?=??.600, ?.421, ?.610, respectively, p?<?0.01). All CT parameters showed significant correlation with PFTs except forced vital capacity (FVC). There was a significant difference in GTI, ATI and Xe-Dyna in each lung area (p?<?0.01).

Conclusions

The parenchymal attenuation change between inspiration/expiration CTs and xenon dynamic change between xenon WI- and WO-CTs correlate significantly. There are alterations in the dynamics of xenon ventilation between areas of emphysema.

Key Points

? The xenon ventilation change correlates with the parenchymal attenuation change.? The xenon ventilation change shows the difference between three lung areas.? The combination of attenuation and xenon can predict more accurate PFTs.

     

Tomosynthesis for the early detection of pulmonary emphysema: diagnostic performance compared with chest radiography, using multidetector computed tomography as reference

Objectives

To compare the diagnostic performance of tomosynthesis with that of chest radiography for the detection of pulmonary emphysema, using multidetector computed tomography (MDCT) as reference.

Methods

Forty-eight patients with and 63 without pulmonary emphysema underwent chest MDCT, tomosynthesis and radiography on the same day. Two blinded radiologists independently evaluated the tomosynthesis images and radiographs for the presence of pulmonary emphysema. Axial and coronal MDCT images served as the reference standard and the percentage lung volume with attenuation values of ?950 HU or lower (LAA_?950) was evaluated to determine the extent of emphysema. Receiver-operating characteristic (ROC) analysis and generalised estimating equations model were used.

Results

ROC analysis revealed significantly better performance (P < 0.0001) of tomosynthesis than radiography for the detection of pulmonary emphysema. The average sensitivity, specificity, positive predictive value and negative predictive value of tomosynthesis were 0.875, 0.968, 0.955 and 0.910, respectively, whereas the values for radiography were 0.479, 0.913, 0.815 and 0.697, respectively. For both tomosynthesis and radiography, the sensitivity increased with increasing LAA_?950.

Conclusions

The diagnostic performance of tomosynthesis was significantly superior to that of radiography for the detection of pulmonary emphysema. In both tomosynthesis and radiography, the sensitivity was affected by the LAA_?950.

Key Points

? Tomosynthesis showed significantly better diagnostic performance for pulmonary emphysema than radiography. ? Interobserver agreement for tomosynthesis was significantly higher than that for radiography. ? Sensitivity increased with increasing LAA _?950 in both tomosynthesis and radiography. ? Tomosynthesis imparts a similar radiation dose to two projection chest radiography. ? Radiation dose and cost of tomosynthesis are lower than those of MDCT.     

Optimal threshold in CT quantification of emphysema

Objectives

To determine the optimal threshold by quantitatively assessing the extent of emphysema at the level of the entire lung and at the level of individual lobes using a large, diverse dataset of computed tomography (CT) examinations.

Methods

This study comprises 573 chest CT examinations acquired from subjects with different levels of airway obstruction (222 none, 83 mild, 141 moderate, 63 severe and 64 very severe). The extent of emphysema was quantified using the percentage of the low attenuation area (LAA%) divided by the total lung or lobe volume(s). The correlations between the extent of emphysema, and pulmonary functions and the five-category classification were assessed using Pearson and Spearman’s correlation coefficients, respectively. When quantifying emphysema using a density mask, a wide range of thresholds from ?850 to ?1,000 HU were used.

Results

The highest correlations of LAA% with the five-category classification and PFT measures ranged from ?925 to ?965 HU for each individual lobe and the entire lung. However, the differences between the highest correlations and those obtained at ?950 HU are relatively small.

Conclusion

Although there are variations in the optimal cut-off thresholds for individual lobes, the single threshold of ?950 HU is still an acceptable threshold for density-based emphysema quantification.

Key Points

? CT is widely used to assess the severity of emphysema ? Density mask technique helps clinicians assess the extent of emphysema with CT ? A standardised cut-off for density mask analysis at lobe level is desirable ? ?950 HU is acceptable for density-based emphysema quantification at the lobar level     

Lung cancer perfusion: can we measure pulmonary and bronchial circulation simultaneously?

Objective

To describe a new CT perfusion technique for assessing the dual blood supply in lung cancer and present the initial results.

Methods

This study was approved by the institutional review board. A CT protocol was developed, and a dual-input CT perfusion (DI-CTP) analysis model was applied and evaluated regarding the blood flow fractions in lung tumours. The pulmonary trunk and the descending aorta were selected as the input arteries for the pulmonary circulation and the bronchial circulation respectively. Pulmonary flow (PF), bronchial flow (BF), and a perfusion index (PI, = PF/ (PF + BF)) were calculated using the maximum slope method. After written informed consent was obtained, 13 consecutive subjects with primary lung cancer underwent DI-CTP.

Results

Perfusion results are as follows: PF, 13.45?±?10.97?ml/min/100?ml; BF, 48.67?±?28.87?ml/min/100?ml; PI, 21?%?±?11?%. BF is significantly larger than PF, P?r?=?0.671, P?=?0.012).

Conclusion

The dual-input CT perfusion analysis method can be applied successfully to lung tumours. Initial results demonstrate a dual blood supply in primary lung cancer, in which the systemic circulation is dominant, and that the proportion of the two circulation systems is moderately dependent on tumour size.

Key Points

• A new CT perfusion technique can assess lung cancer's dual blood supply.
• A dual blood supply was confirmed with dominant bronchial circulation in lung cancer.
• The proportion of the two circulations is moderately dependent on tumour size.
• This new technique may benefit the management of lung cancer.

     

Value of a Dixon-based MR/PET attenuation correction sequence for the localization and evaluation of PET-positive lesions

Purpose

In this study, the potential contribution of Dixon-based MR imaging with a rapid low-resolution breath-hold sequence, which is a technique used for MR-based attenuation correction (AC) for MR/positron emission tomography (PET), was evaluated for anatomical correlation of PET-positive lesions on a 3T clinical scanner compared to low-dose CT. This technique is also used in a recently installed fully integrated whole-body MR/PET system.

Methods

Thirty-five patients routinely scheduled for oncological staging underwent ¹⁸F-fluorodeoxyglucose (FDG) PET/CT and a 2-point Dixon 3-D volumetric interpolated breath-hold examination (VIBE) T1-weighted MR sequence on the same day. Two PET data sets reconstructed using attenuation maps from low-dose CT (PET_{AC_CT}) or simulated MR-based segmentation (PET_{AC_MR}) were evaluated for focal PET-positive lesions. The certainty for the correlation with anatomical structures was judged in the low-dose CT and Dixon-based MRI on a 4-point scale (0?C3). In addition, the standardized uptake values (SUVs) for PET_{AC_CT} and PET_{AC_MR} were compared.

Results

Statistically, no significant difference could be found concerning anatomical localization for all 81 PET-positive lesions in low-dose CT compared to Dixon-based MR (mean 2.51?±?0.85 and 2.37?±?0.87, respectively; p?=?0.1909). CT tended to be superior for small lymph nodes, bone metastases and pulmonary nodules, while Dixon-based MR proved advantageous for soft tissue pathologies like head/neck tumours and liver metastases. For the PET_{AC_CT}- and PET_{AC_MR}-based SUVs (mean 6.36?±?4.47 and 6.31?±?4.52, respectively) a nearly complete concordance with a highly significant correlation was found (r?=?0.9975, p?Conclusion Dixon-based MR imaging for MR AC allows for anatomical allocation of PET-positive lesions similar to low-dose CT in conventional PET/CT. Thus, this approach appears to be useful for future MR/PET for body regions not fully covered by diagnostic MRI due to potential time constraints.     

Diagnostic accuracy of unenhanced, contrast-enhanced perfusion and angiographic MRI sequences for pulmonary embolism diagnosis: results of independent sequence readings

Objectives

To independently evaluate unenhanced, contrast-enhanced perfusion and angiographic MR sequences for pulmonary embolism (PE) diagnosis.

Methods

Prospective investigation, including 274 patients who underwent perfusion, unenhanced 2D steady-state-free-precession (SSFP) and contrast-enhanced 3D angiographic MR sequences on a 1.5-T unit, in addition to CTA (CT angiography). Two independent readers evaluated each sequence independently in random order. Sensitivity, specificity, predictive values and inter-reader agreement were calculated for each sequence, excluding sequences judged inconclusive. Sensitivity was also calculated according to PE location.

Results

Contrast-enhanced angiographic sequences showed the highest sensitivity (82.9 and 89.7 %, reader 1 and reader 2, respectively), specificity (98.5 and 100 %) and agreement (kappa value 0.77). Unenhanced angiographic sequences, although less sensitive overall (68.7 and 76.4 %), were sensitive for the detection of proximal PE (92.7 and 100 %) and showed high specificity (96.1 and 99.1 %) and good agreement (kappa value 0.62). Perfusion sequences showed lower sensitivity (75.0 and 79.3 %), specificity (84.8 and 89.7 %) and agreement (kappa value 0.51), and a negative predictive value of 84.8 % at best.

Conclusions

Compared with contrast-enhanced angiographic sequences, unenhanced sequences demonstrate lower sensitivity, except for proximal PE, but high specificity and agreement. The negative predictive value of perfusion sequences was insufficient to safely rule out PE.

Key Points

? Unenhanced angiographic MR sequences are very specific and can identify proximal PE. ? Contrast-enhanced MR angiographic sequences show high sensitivity for PE diagnosis. ? A normal MR perfusion result does not exclude PE. ? Inter-reader agreement is better for angiographic than perfusion MR sequences.     

Potential of right to left ventricular volume ratio measured on chest CT for the prediction of pulmonary hypertension: correlation with pulmonary arterial systolic pressure estimated by echocardiography

Objectives

To investigate the correlation of right ventricular (RV) to left ventricular (LV) volume ratio measured by chest CT with pulmonary arterial systolic pressure (PASP) estimated by echocardiography.

Methods

104 patients (72.47?±?13.64?years; 39 male) who had undergone chest CT and echocardiography were divided into two groups (hypertensive and normotensive) based upon an echocardiography-derived PASP of 25?mmHg. RV to LV volume ratios (RV_V/LV_V) were calculated. RV_V/LV_V was then correlated with PASP using regression analysis. The Area Under the Curve (AUC) for predicting pulmonary hypertension on chest CT was calculated.

Results

In the hypertensive group, the mean PASP was 46.29?±?14.42?mmHg (29-98?mmHg) and there was strong correlation between the RV_V/LV_V and PASP (R?=?0.82, p?V/LV_V were 0.990 and 0.892. RV_V/LV_V was 1.01?±?0.44 (0.51-2.77) in the hypertensive and 0.72?±?0.14 (0.52-1.11) in the normotensive group (P <0.05). With 0.9 as the cutoff for RV_V/LV_V, sensitivity and specificity for predicting pulmonary hypertension over 40?mmHg were 79.5?% and 90?%, respectively. The AUC for predicting pulmonary hypertension was 0.87

Conclusion

RV/LV volume ratios on chest CT correlate well with PASP estimated by echocardiography and can be used to predict pulmonary hypertension over 40?mmHg with high sensitivity and specificity.

Key Points

? Chest CT is widely used in patients who may have pulmonary hypertension. ? Cardiac ventricular volume ratios on chest CT correlate with pulmonary arterial systolic pressure. ? A R/L ventricular volume ratio >0.9 usually indicates pulmonary hypertension >40?mmHg. ? Information available on routine chest CT may help predict pulmonary hypertension.     

Characterisation of solitary pulmonary lesions combining visual perfusion and quantitative diffusion MR imaging

Objective

To evaluate the diagnostic accuracy of dynamic contrast-enhanced (DCE) magnetic resonance (MR) and diffusion-weighted imaging (DWI) sequences for defining benignity or malignancy of solitary pulmonary lesions (SPL).

Methods

First, 54 consecutive patients with SPL, clinically staged (CT and PET or integrated PET-CT) as N0M0, were included in this prospective study. An additional 3-Tesla MR examination including DCE and DWI was performed 1 day before the surgical procedure. Histopathology of the surgical specimen served as the standard of reference. Subsequently, this functional method of SPL characterisation was validated with a second cohort of 54 patients.

Results

In the feasibility group, 11 benign and 43 malignant SPL were included. Using the combination of conventional MR sequences with visual interpretation of DCE-MR curves resulted in a sensitivity, specificity and accuracy of 100 %, 55 % and 91 %, respectively. These results can be improved by DWI (with a cut-off value of 1.52?×?10^?3 mm²/s for ADC_high) leading to a sensitivity, specificity and accuracy of 98 %, 82 % and 94 %, respectively. In the validation group these results were confirmed.

Conclusion

Visual DCE-MR-based curve interpretation can be used for initial differentiation of benign from malignant SPL, while additional quantitative DWI-based interpretation can further improve the specificity.

Key Points

? Magnetic resonance imaging is increasingly being used to help differentiate lung lesions. ? Solitary pulmonary lesions (SPL) are accurately characterised by combining DCE-MRI and DWI. ? Visual DCE-MRI assessment facilitates the diagnostic throughput in patients with SPL. ? DWI provides additional information in inconclusive DCE-MRI (type B pattern).     

Emphysema progression is visually detectable in low-dose CT in continuous but not in former smokers

Objectives

To evaluate interobserver agreement and time-trend in chest CT assessment of emphysema, airways, and interstitial abnormalities in a lung cancer screening cohort.

Methods

Visual assessment of baseline and fifth-year examination of 1990 participants was performed independently by two observers. Results were standardised by means of an electronic score sheet; kappa and time-trend analyses were performed.

Results

Interobserver agreement was substantial in early emphysema diagnosis; highly significant (p?Conclusions Visual scoring of chest CT is able to characterise the presence, pattern, and progression of early emphysema. Continuous smokers progress; former smokers do not.

Key Points

? Substantial interobserver consistency in determining early-stage emphysema in low-dose CT. ? Longitudinal analyses show clear time-trends for emphysema presence and grading. ? For continuous smokers, progression of emphysema was seen in all lung zones. ? For former smokers, progression of emphysema was undetectable by visual assessment. ? Onset and progression of interstitial abnormalities are visually detectable.     

Dual-energy CT lung ventilation/perfusion imaging for diagnosing pulmonary embolism

Objectives

To evaluate the feasibility and findings of combined dual-energy computed tomography (DECT) lung ventilation/perfusion imaging in patients with suspected pulmonary embolism (PE).

Methods

This study was institutional review board-approved and written informed consent was obtained from each patient. Thirty-two subjects (aged 11–61 years) underwent combined xenon-enhanced ventilation and iodine-enhanced perfusion DECT. Ventilation, perfusion and morphological information were visually interpreted. Ventilation/perfusion information was classified as mismatch (differing patterns) or match (concordant patterns). Adverse reactions and radiation doses were recorded for each subject.

Results

Of 32 patients undergoing xenon-enhanced DECT, six patients reported adverse reactions (shortness of breath, n?=?2; mild dizziness, n?=?3; limb numbness, n?=?1). Twenty-eight of 32 patients could be included into the data analysis. PE was detected in 10/28 patients. PE-related ventilation/perfusion mismatch was found in 17 lung lobes in 8/10 patients and matched ventilation/perfusion was detected in 2 patients. Eighteen patients had no PE. In this group, there was no case of a ventilation/perfusion mismatch. Matched ventilation/perfusion impairment was seen in one patient. The overall radiation dose from two DECT acquisitions was 4.8?±?1.4 mSv (range 2.7-7.5 mSv).

Conclusions

DECT lung ventilation/perfusion imaging is feasible and can visualise ventilation/perfusion match or mismatch in patients with suspected PE.

Key Points

? Combined dual-energy CT lung ventilation/perfusion imaging is feasible. ? Combined dual-energy CT ventilation/perfusion imaging provides lung morphological and functional information. ? Dual-energy CT can demonstrate ventilation/perfusion mismatch in patients with pulmonary embolism.     

Diagnostic accuracy of contrast-enhanced MR angiography and unenhanced proton MR imaging compared with CT pulmonary angiography in chronic thromboembolic pulmonary hypertension

Objective

To evaluate the diagnostic accuracy of contrast-enhanced MR angiography (CE-MRA) and the added benefit of unenhanced proton MR angiography compared with CT pulmonary angiography (CTPA) in patients with chronic thromboembolic disease (CTE).

Methods

A 2?year retrospective study of 53 patients with chronic thromboembolic pulmonary hypertension who underwent CTPA and MRI for suspected pulmonary hypertension and a control group of 36 patients with no CT evidence of pulmonary embolism. The MRI was evaluated for CTE and the combined diagnostic accuracy of ce-MRA and unenhanced proton MRA was determined. CE-MRA generated lung perfusion maps were also assessed.

Results

The overall sensitivity and specificity of CE-MRA in diagnosing proximal and distal CTE were 98% and 94%, respectively. The sensitivity improved from 50% to 88% for central vessel disease when CE-MRA images were analysed with unenhanced proton MRA. The CE-MRA identified more stenoses (29/18), post-stenosis dilatation (23/7) and occlusions (37/29) compared with CTPA. The CE-MRA perfusion images showed a sensitivity of 92% for diagnosing CTE.

Conclusion

CE-MRA has high sensitivity and specificity for diagnosing CTE. The sensitivity of CE-MRA for visualisation of adherent central and lobar thrombus significantly improves with the addition of unenhanced proton MRA which delineates the vessel wall.